Prior to Baldur's Gate, many games were made based on D&D, and most of them were VERY faithful adaptations of the 1st and 2nd edition rules. Including the 10+ Gold Box games and the two Dark Sun games, all of which hewed quite closely to the parent ruleset and gameplay style.
Then BioWare got their chance to make a D&D game. And they decided, based on their own personal opinions as video game designers, to make significant changes to the system because they felt that it would be more fun (or sell better, some of both probably) than keeping their game as tight to the 2e rules as the prior D&D titles. And now Larian is doing the exact same thing.
But on Reddit and on the Larian forums, we've got a lot of people pretending that Baldur's Gate 1+2 was some kind of deeply faithful adaptation, and Baldur's Gate 3 is a wild departure. I think people are kidding themselves.
Baldur's Gate took a game in which each character takes their turn individually, in order, and changed it into a wild melee where everyone acted at the exact same time. That is a HUGE change. The impact on how fights play out in such a system is quite significant, and they way it FEELS to play it is even more massive. The ability to pause and issue commands does not change the fact that any time you have it unpaused, everyone is acting simultaneously. That's the single biggest change to D&D in a video game of all time.
In addition to this, Baldur's Gate 1+2 changed the way a number of spells worked, to fit better with their new system. I can't tell you exactly how many, as I'm not prepared to comb through all the spell descriptions for an hour to gather that data. But it was a not insignificant number.
This is not, by the way, a "turn-based is better than real-time-with-pause!" argument. I'm not in any way saying that what Bioware did was BAD. I'm not in any way saying that the system they pioneered, and which was subsequently used by many other excellent isometric RPGs, is BAD. If they had stuck with turn-based, Baldur's Gate 1 might have been a WORSE game for it. I don't even know. I'm only saying that it is a BIG, highly impactful change to D&D-as-simulated-by-a-computer. Bigger than any change that Larian has made. And it wasn't Bioware's only change, either, so let's not pretend that it was.
Bioware didn't HAVE to make Baldur's Gate that way. There was already plenty of precedent of beloved, successful D&D licensed CRPGs out there which stuck much closer to the tabletop rules. But they were the video game designers, and they were making a video game, and they felt/judged/decided that their game would be better if they made these changes. They made that decision because they were the ones adapting D&D to THEIR game. And now, Larian is just doing the SAME thing.
And I'm not gonna say that "no one complained about that at the time" because no, people definitely complained about it at the time. But NOW, you got a lot of people who seem to ignore how significantly Bioware altered D&D to make Baldur's Gate 1+2. Now, you have a lot of complaints that suggest that the old Baldur's Gate games were super close to actual D&D and Larian's sequel is just changing the rules willy-nilly with no reason and with no justification. But no, they are not doing anything more than Bioware did. To my reckoning, as a player of D&D for 35 years, they are changing D&D LESS than Bioware did.
TL;DR: Making some developer decisions to creatively alter the D&D rules in order to make what they believe and hope will be a more fun video game is not some new, unique crime of Larian Studios. It is, in fact, core to the Baldur's Gate franchise legacy.