As more and more DLCs get released, Paradox's habit of adding penalties in the free patch and locking the solution behind a paywall causes the base game to become more unbalanced as time goes on. Development/institutions is the most obvious example of this, but there are many others. Liberty desire in subjects introduced in a free patch, but most ways of reducing it are locked behind a paywall. The post-common sense building system was introduced in a free patch, but the only to get more building slots is locked behind a paywall, and many of the bonuses the old system gave were replaced with things in newer DLCs like strengthening government, estates, and government ranks. The ability to get support independence is locked behind a paywall, making vassal nations nearly impossible to play in the current version of the base game. All the espionage actions the AI spams you with are part of the free patch, but the only counter to it (counterespionage) is locked behind a paywall

The ability to mix and match DLCs sounds great in theory, but with over 2000 possible combinations of expansions as of Third Rome, there's simply no way to test every possible combination and that leads to a horribly unbalanced and buggy experience if you have some DLCs but not others. One example Reman gives is that you can promise land to your allies with the Cossacks DLC, but if you don't have Common Sense then you can't actually transfer occupation to them; this makes it much harder to actually give them the land you promised. There's probably many more examples that he didn't mention, but Paradox balancing their game around you having every DLC makes the full EU4 experience extremely expensive. Even then, they simply refuse to address longstanding balance issues and major exploits in favor of pumping out new features to make into DLCs.

The perceived value of DLCs is diminished by the lack of focus and arbitrary inclusion of features most people don't care as much about. Common Sense is considered a must-have expansion because of development, but its $15 price tag also includes HRE free cities, government ranks, Buddhist karma, Protestant church power, parliaments for constitutional monarchies, and better theocracies. The Rights of Man promo picture features a portrait of Frederick the Great, but its $20 price tag also includes the Ottoman government, new Coptic and Fetishist features, the great power system, and lots of quality-of-life improvements to all monarchies like consorts and disinheriting/abdicating. Third Rome was a step in the right direction in this respect, but they still messed that up because they combined the cosmetic unit pack with the expansion to make it way more expensive than it should be for people who don't care about the cosmetic stuff.

The nature and sheer number of DLCs causes a lot of confusion, especially for new players, creating an even bigger barrier to entry for a game that already has a steep learning curve. The unfocused nature of the DLCs frequently leaves people asking "what DLC do I need to do x strategy or y thing?", something that should not be nearly as common of a question. When people go to the Steam page for EU4, they are greeted by a giant wall of DLCs with no indication of which ones are important and which ones aren't. Content Packs sound like they would be new missions or events, when in reality they're entirely cosmetic. Third Rome being an immersion pack would sound like it's just new unit models, when in reality it's a full blown expansion, albeit with a narrower scope than most. The lack of any bundle containing just the expansions leads uninformed new players to be appalled at the $300 price tag of getting everything, when in reality if you only care about the expansions it's more like $100 or less on sale. And even if you know not to get the content packs, you still have to go search up the wiki or reddit to figure out which expansions are the most necessary. Both me and Reman have had major issues trying to get new players into the game, because our friends see that massive $300 price tag and are instantly turned off without even doing more research. This price tag is artificially kept high because Paradox (unlike most major game publishers) refuses to lower the price of older DLCs for years after they're released, only slightly reducing the price of older games when a sequel comes out.

Having the DLC be optional forces mechanics to essentially exist in isolation, not really effecting anything outside of themselves and having their own requirements and penalties/bonuses. This works fine for some things like region- or country-specific features like the Prussian monarchy, but much of the time it leads to mechanics that feel completely out of place. Like everyone's favorite: estates. They're a neat little system that every country has access to, and each estate has its own rewards and penalties which is effectively a very rewarding minigame if you're willing to micromanage them. Except, they're completely divorced from every other aspect of gameplay and you could completely ignore them for the whole game if you wanted to. The only way they affect anything other than themselves is the bonuses/penalties that get spit out of them. The devs may as well have inserted a game of Galaga that you play every 20 years, and if you got the same rewards out of it as estates, it would feel exactly as connected to the rest of the gameplay as estates do. Quite tragic considering how there are many obvious ways estates could have interacted with other game mechanics to add to the experience and add new ways of playing. Reman thinks there's not really any good way to fix this, but I think it would be great if estates were overhauled as part of a free patch in the future. They already have the capability of adding DLC-specific features in the free patch, so I don't see why this wouldn't be possible.

The current DLC policy poisons goodwill with the community, making many diehard fans second guess their future purchases from Paradox. I know with me personally I'm a huge EU4 fan and would love to expand into other Paradox games, but with the many things I've been reading about how base HOI4 is a shell of what it could have been, it's obvious to me that Paradox hasn't learned a thing from their community and just want to milk the game for lots of DLC money later, giving me much less reason to buy it. CK2 seems to be much like EU4 in that it has $300 worth of DLC, but most of those aren't necessary and there's no obvious way for a potential new player like me to figure out which ones are necessary or if even just the base game works fine. That leaves me with just Stellaris, which I've heard good things about and might look into, but learning a new Paradox game is very difficult and time consuming task and I'm still having tons of fun with EU4 after 2500+ hours. The price hike especially poisoned a ton of good will with the community, and while that's not going to have a huge immediate effect on Paradox's bottom line, it effectively confines their games to a stagnant player base as fewer and fewer fans recommend them to new players. I know I'll definitely have second thoughts about buying the eventual EU5, much less recommending it to my friends.