It was marketed as a Turn Based Close to Tabletop D&D Experience. We are not getting that. End of story.
Is there a source that says Larian wanted to create an authentic TT RPG? [...] I don't remember Larian guaranteeing or even promising such a thing.
I tried to answer that question in that post, a little while ago (motivated by a similar question from someone else). My understanding of Larian's vision has probably improved since then, but the core of my post was looking at 4 interviews Larian gave, where they talked about the rules and the DnD/tabletop feel, and what they said won't change.
I wasn't able to provide a definite, clear-cut, yes/no answer to the question. But I found their communication to send mixed signals, saying both "it will be quite close/just some tweaks" and "oh we only focus on a game we'll enjoy playing, not so much on the RAW". And I think that it is very understandable that, as a result from Larian's communications, some players were expecting more faithfulness to the rules.