I am one of those people who has played BG1/BG2/IWD1/IWD2/PoE1/PoE2 for countless hours. And played with this "real time" combat both back when it was first released and with the newer games that use it. And I simply cannot see how people prefer it over the turn-based combat system.
The amount of time I lost by having to pause/unpause, pause/unpause, pause/unpause, plus the time I lost by having to reload because my companions ran into my Fireball/Flamestrike/Bladebarrier or walking/pathing got stuck, simply made the game very slow. The amount of times I got frustrated because the game mechanics would not let me do what I wanted or just simply got stuck was unreal.
Yes, it's "faster" when you have to fight 4 low level bandits x 100 times. But that was never a fun part of the BG games. In Divinity games - and from what the demo showed us it's the same in BG3 - every encounter is memorable. Even when in your mind the encounter was "the one with the big bouncy dude that blows the trumpets with the 2 wolves and the 4 little gremlins by the lighthouse", it is memorable. How many people remember those 4 bandits from BG2? No not those. Not those either. The 34th group of 4 bandits from the 100 groups of 4 bandits you fought. Yeah that one. Do you remember it?
I remember every single encounter from both Divinity OS games. Every single one.
Still, I get the frustration from those who wanted this "fake real time" combat. If you prefer something, you will be disappointed when it's not the thing you prefer. I'm just glad they are offering a system that allows both truly tactical combat and meaningful encounters throughout the game.