I don't see an issue with how Larian has communicated in regards to what they were planning to do. They were clear it would be a fun game based on DnD 5e and that it would use the Divinity engine. That is pretty much exactly what they delivered thus far.
And if the game was named Divinity: A Forgotten Realms Adventure, many of us would be silent - at least those of us that care more about BG3 being a Baldur's Gate game rather than being a faithful D&D 5e game. But the game's name is Baldur's Gate 3 and right now, it sure seems right now like a false advertisment and nostalgia cashgrab. In the history of cRPGs (and dungeons), there were many D&D games set in Forgotten Realms, that didn't make them Baldur's Gate games.
And it's not a one specific thing - I don't care for RTwP, AD&D, actually not necessarily even the Forgotten Realms setting - it's almost every design decision Larian went for (their comfort zone is DOS and it seems they will never leave it) is in conflict with it being a worthy sequel.
