Then how do you explain RTwP games having a TB option? This same argument should equally apply there as well, yet the TB mode in P:Km works very well according to TB fans themselves. Seems like this is a very convenient one-sided argument being made only from the TB side, that all RTwP games should have a TB option but not vice versa because TB games cannot have a RTwP mode something something. I don't buy it for even a second. Seems like a self-serving argument from TB fans so that they can have everything their way.
We don't really know how difficult it is to accommodate both. We can only speculate. It might be easier to add TB to a RTwP game, or vice versa, or more likely, depends on the mechanics of the game itself. As for Kingmaker, if I understand correctly, the game had an underwhelming reception, so it was in their best interest (i.e $$) to try to make it more appealing/accessible. Conversely, DOS2 had no such need to add a RTwP option, because of how well the game did (and probably continues to do). If it hasn't started already because of the success of DOS2, a hit with BG3 might spell the end of RTwP (or slumber, at least).