I'm not following.
Would you play chess with checkers ru!es? Why would you play D&D 5e with another ruleset?
All people are trying to suggest is make the game more like 5e which it is based on, not because it's the greatest system ever.
And to add to this, people aren't just saying make the game closer to 5e. People are protesting because the some of the changes (and the total omission of certain features) have only served to create wildly worse imbalance rather than make the game any interesting on a tactical level. Going 'lol DnD isn't balanced!' as a defense means you don't actually have a real argument, because it's actually more balanced than whatever we have now.
If height advantage/low ground disadvantage/backstab advantage didn't exist, and if player-controlled reactions/dodge action/ready actions did, people would have likely been perfectly fine with literally everything else staying as is. I know I would be.
I used to think D:OS2 was a revolutionary game, and it really is. But as the years passed, I started to realize I didn't actually enjoy the combat due to how the game's difficulty was largely balanced around the idea that you'd cheese everything you could. One could say I only enjoyed the
idea of the game's combat, but not actually doing it at the end of the day. Especially when late game boss fights weren't really very tactical - they were just rocket tag on an extreme scale. If the boss ever got a turn with a party member nearby that either wasn't out of range due to height restrictions or didn't have chameleon cloak/tons of defensive buffs stacked up, that party member (or maybe your entire party if they weren't completely split up far enough away from each other, because almost every late game boss moved by teleporting themselves) was guaranteed to die no matter what. There's a reason why the majority of the D:OS2 community says the game peaked in Act 2.
I mean, really, this is how I won the vast majority of fights in D:OS2 Tactician with a full party (which is MUCH harder than a lone wolf run, which most people did to beat Tactician) with little difficulty, once I figured out how the game really worked.
1: Give everyone level 2 in Aeroteurge so they get Teleport and Nether Swap
2: Split up the party, have everyone start in stealth from high ground. Maybe send one person ahead, usually your tankiest or highest initiative party member forward to initiate dialogue before the battle if necessary. (Highest initiative so they can bunch enemies up with a combination of Teleport/Nether Swap to simultaneously bunch enemies up, and get out of immediate danger with the latter at the same time.) This was often actually my archer MC, who would have enough AP remaining for 1 attack after they got out of danger with one of his mobility skills or swapping places with a high ground enemy with Nether Swap.
3: Maybe have the other party members cast buffs on them during dialogue, because buff timers are frozen while talking, then go back to stealth afterwards.
4: Once combat actually begins, have your other party members immediately teleport enemies/AoE burst enemies from stealth to disable their first turn or cull them outright.
(I favored having two Hydrosophists using Rain/Ice spells to freeze enemies, with one also focusing on further Aeroteurge spells for stuns. Sometimes they'd spam Rain before the fight to coat the ground in water and reveal invisible enemies. My archer had elemental arrows to help facilitate the status effects if needed. This usually resulted in most enemies having their first turn completely denied if they didn't immediately die. If an enemy survived and was able to move, another party member would just teleport them right back in if they lacked the ability to cast Fortify on themselves. And if they did use Fortify, their health was usually already low enough that they'd be finished off by any magic attack anyway. Note that you can also use Nether Swap to swap living characters with dead bodies.)
5: Spend the following turns cleaning up.
That's really D:OS2 combat in a nutshell. Don't do anything like this, and the game outside of specific boss fights suddenly becomes 5x as hard. Field effects didn't actually matter much for damage reasons if you were playing optimally, they were far more dangerous because of any status effects tied to them, due to everyone's extreme mobility and the armor system blocking the damage portion unless you were dumb enough to actually move within those field effects.
That said, what I just described about D:OS2 requires a lot of effort and smart tactical thinking with how skills interacted in that game.
It's very clear that at the moment, a lot of the same design philosophy seeped into BG3. Yet it is somehow even MORE restrictive in options than D:OS2 was on that front, with most fights summed up as 'get to high ground ASAP and have everybody else attack/shove/barrelmancy things from stealth'', and it doesn't help when a lot of the core tactical features like player controlled reactions and ready actions are missing. It's rather disheartening for lack of a better word.