Just because someone wants to play the game a certain way doesn't always mean it should be allowed.
In short because most players won't be able to design fun experience for themselves. If they were, there would be no need for games and game designers, and a game engine, like Unity would suffice.
I said it many times but I will say it again: I don't pay £50 for a game, to then have to sit down and design it. I expect it to be a designed for me, with a ruleset that works and is fun to play. Exploits as they are in BG3 are hardly exploits they are broken mechanics. Stealth in BG3 is broken. It doesn't work. One either doesn't use it, or will find that it trivilizes combat.
Of course, Larian may believe that creating broken, exploitative mechanics is fun, and there we can just agree to disagree, and I will be upstet that they get to handle IP that I like very much and hopefully avoid their titles in the future.