So I got curious and went to the website and steam to see what was said. Does anyone have source material for where they said BG3 would 100% follow the D&D rule set exactly? That seems to be the issue with the rule purists. That the game was advertised as following the core rules 100% and it isn't.
So I started looking around as I haven't really paid much attention to how they marketed it. I assumed it was based on the ruleset and like any change in medium, and company, they would adapt it to a computer game and put their own stamp on it. That seems very reasonable to me and to be expected.
I do expect a game that says they are based off D&D rules to have that basic feel/atmosphere of a D&D like game and for me they do. As soon as I started playing I felt right at home making a character, rolling the dice, seeing familiar classes, races, stats, magic spells, etc.,. It all felt very D&D to me in making my character. The atmosphere, the various monsters and critters, all felt like a D&D inspired game.
Now if a game said they would be based of D&D and then it was something like Skyrim I would be annoyed as they are pretty different rule sets and styles.
Anyhow the actual website for BG3 that I found was completely useless. Talk about bad design. There wasn't any clear place to find general information unless the video was meant to do that, which I didn't watch as I prefer reading:
https://baldursgate3.game/
Now on Steam it did mention it:
https://store.steampowered.com/app/1086940/Baldurs_Gate_3/
"… based on the D&D 5e ruleset. Team-based initiative, advantage & disadvantage, and roll modifiers join combat cameras, expanded environmental interactions, and a new fluidity in combat that rewards strategy and foresight."
Although it says based on the ruleset which to me means they use it as a base and then go from there. It's just providing the base not the whole thing.
From WIKI:
https://en.wikipedia.org/wiki/Baldur's_Gate_III
The game will be based on the 5th-edition Dungeons & Dragons rule set, though it will include tweaks and modifications that Larian found necessary in translating it to a video game. For example, the combat system is expected to be weighed more in favor of the player than in the tabletop version, to make the game more enjoyable.[3]
Read some articles, like this one:
https://www.pcgamesn.com/baldurs-gate-3/dungeons-and-dragons-fifth-edition
Where at first they imply it will be very faithful … but later clarify to state they will adjust it to fit the computer medium.
It suggests maybe people were reading more into how pure the rules and implementation were meant to be. At least I am finding disclaimers that indicate it wasn't meant to be an exact and strict implementation. So with that in mind even if I cared for a pure implementation I would not have expected it with this game based on what I was reading.