PSA: when you accuse someone of being disingenuous you are claiming that they are being insincere, either by intentionally lying or omitting relevant information. It isn’t just something you say when you disagree with someone.

Sequel can mean lots of different things in games. Some sequels continue a story or even just a setting and a premise but are in different genres. Resident Evil 4, Gand Theft Auto 3, Red Dead Redemption, Fallout 3, and Metal Gear Solid are all mechanically as different from their predecessors as Baldur’s Gate 3 is to BG1 and 2. I think whether or not you consider these proper sequels is irrelevant to the question of whether or not BG3 should be titled as it is. There is plenty of precedent in video games for this. It’s not anything new.