If you watch History and medieval warfare focused YouTube channels (Like Scholagladiatoria, Tods Workshop and all connected ones) or have a general interest in military history which I guess many of the BG3 target audience might then you know that any realism is basically impossible with a system like DnD or 99% of all other RPG and action games.
Even games like Kingdom Come: Deliverance or Mordhau which are more authentic than most and really good in their novel approach and also a totally different game genre don't even come close.
I do watch those channels and you are right - there is no way a computer game is ever going to capture the complexity and nuance of something that requires full-body engagement and reactions.
But it doesn't have to. The goal isn't accurate 1:1 simulation, it is just a BETTER simulation than what you usually get.
Historically DnD and RPGs in general have been responsible for the worst systems from a realism perspective like Armor Class and Hit Points or DnD weapon stats. The focus has clearly been epic adventuring and the hero fighter being able to slay hordes of orcs over any realism. Also coming originally from a tabletop miniature game the math has always been very simple and fast.
I don't mind hit point, I mind hit point inflation. If you were to get 10HP per constitution point and if it didn't change (or maybe change minimally... like 1 HP per level), I'd be fine with it.
Armor Class though, I don't like. I understand why it was made as it was (to make calculations fast and to make all armors valid), but I don't like it. For one, the idea of all armors being essentially equal disgusts me. For another, the system makes light and heavy armor function virtually the same.
I do admit, aside from giving light armor using classes doge/agiltiy buffs, I struggle to find a good way to implement proper armor. The class-based system (and it's bajillion redundant and stupid sub/prestige-classes) and it's limitations sometimes irk me to no end.
As Sordak said if you allow too many things that are possible in RL then they will be quickly OP compared to vanilla actions. 5e tries to keep the mechanics simple. Like in 3e/3.5 there was all kinds of things like more resistances (bludg/slash/pierce), more stuff possible with Attacks of Opportunity or things like mounted lance charge and a multitude of feats which also lead to the most OP powergaming exploit options in any edition.
5e made everything pretty simple and stopped the influx of additional unbalanced options.
This is why I'm not a big fan of special moves, especially common ones like "shield bash", "pommel strike". All of those should be automatic. PArt of hte standard attack/moveset.
