Chess is a different case.
Most "ugoigo" so called RPGs are based on luck. This changes totally the decision making process (which belongs to optimization of luck patterns) Chess resolution is based on hard relation between pieces. Chess have more in common with real time games than most "ugoigo" have with chess.
Real time games usually rely on hard resolution in order to introduce a benchmark for skills.
Like: without micro, unit A beats unit B, with proper micro, unit B beats unit A.
In chess, the end of a game might be announced ahead because of this.
In a game like wasteland 2, that relies on luck, resolutions with 5 per cent success chances are dealt no different from resolutions with 95 per cent failure chances.
You can take them both, fail the first and succeed the second.
In most "ugoigo" products, uncertainty is produced by lack of luck.
In real time games, uncertainty is produced by lack of skills.
Being good at playing real time doesn't mean having a superior intellect as you seem to suggest, specially when for the most part it is based on basic actions learnt and repeated over and over until it is executed without thinking at the highest speed.
It was not put in terms of superiority. It was put in terms of basic requirements to play a game.
Now it might be hard to argue against the basic requirements to play real time games as being perceived as superior. That was not being the point.
As to the rest, it does not happen that way automatically. A game like PoE gives the opportunity to separate the thinking act from the execution (scouting was supposed to be done all the time, giving the player all the time in the world to design the plan to be executed in real time just after.
In other games, the thinking act is not as separated and it is part of the skillsets to learn how to buy time in order to think the plan of action.
Not the case of PoE, that if, it is required higher skills, do not require that high skills.
I agree that people with fast thinking skills might be better at it, but that doesn't make them more intelligent or skilful, just as a 100m runner is not a better athlete than a marathon runner.
Marathon runners run marathons. Dashers run dashes.
In the game case, it is about fighting the same combat under different forms.
The same fight might fought in real time or in "ugoigo" sequence.
On the other hand skills though partly innate are also acquired. So I don't think there are people who "can't" play real time. I think any normal person can play real time with sufficient skill, but some just don't bother going through the training process as the experience is not satisfactory.
When will veteran players exert themselves in order to gain the skills?
That's the wall hit by PoE: thinking that, out there, there were still players with the modicum of skills required to play PoE. There were not. Either players did not have the skills or when they have, they did not bother to play PoE because they prefer to employ their skill sets on other games (that are more demanding than PoE)
I also feel that real time systems, in which you must take decisions for multiple characters at the same time, are completely unnatural.
On what ground?
Roleplaying several characters at once should also be completely unnatural. Does not prevent so called RPGers to tell that party based games are role playing games.