Is your argument that The Forgtten Realms is a nonsense non-setting where anything goes and everything is fine and acceptable at any point?
No, my argument is that WotC determines what is and what isn't canon. Not some random forum user.
The consumers feelings do in fact matter because who do you think the setting is being made for?
The setting is being made for whomever will give WotC money. Whether this is long established fans, or new ones. They don't care. So long as they make money.
If WotC introduces lightsabers, blasters and the force they might alienate their existing fans, but they might also attract in a ton of Star Wars fans (And a massive lawsuit from Disney, but I digress) which could be acceptable if they still made acceptable profits.
Though, it's not like things being in a setting necessarily dictate much. Since it's up to other writers whether they include certain things in their stories. Like, if BG3 included iPhones and helicopters, it doesn't necessarily mean every future writer making a story set in FR has to include them. At worst all that would be necessary is for a BG4 to either include them or include a pretense for lacking them.
If BG3 had been a failure and people had been complaining about how it didn't fit the pre-established tone of the setting, do you think WotC would stick to their guns and say that it's absolutely canon? No, they'd ignore its canonicity.
Sure. But we don't live in that world.
We live in a world where BG3 is a success and is canon. Ergo, everything in it is canon, despite any gripes of random people on a forum.
The implication of your argument is that fans should just silently take whatever they're given as though WotC is doing them a favor.
When did I say that?
People are well within their right to complain about anything they like. It doesn't mean WotC will bend over backwards to cater to them.
My argument merely is that WotC has the final say on what is or isn't acceptable in THEIR IP.
Perhaps mass backlash might influence their decision, like if BG3 was a massive flop specifically because of something it introduced to the setting. But ultimately, it's under their control and it's their decision about what is or isn't canon.
If George RR Martin were to say in the next Game of Thrones book that it's canon that cell phones exist and people travel around on motorcycles, then that's as much canon as anything going on with BG3 and the forgotten realms. You could argue that "since he's the author and IP holder, he's entitled to make the setting anything he wants" and it would be just as valid as what you're saying about WotC. People would still have every right to complain about it, dislike it, and stop buying the books.
How is that in any way relevant?
If George RR Martin added that stuff into his next book. People can complain. But it won't necessarily mean that the book stops being canon.
If people complain and then George RR Martin declares the book non-canon as a result. That is the only time the consumer sentiment influences the canon of his IP.
The point being made was that Larian did not like the forgotten realms as it had existed before they were allowed to influence it, and as evidence, KR pointed to a number of things Larian included that run counter to the setting as it had previously been presented. It doesn't matter that those things can be allowed if WotC says they are, what matters is that they weren't there before and Larian added them in because they were unsatisfied with the setting as they had recieved it. The argument is that if Larian had been happy with the setting, they would not have added the things they did. What is and isn't canon is another discussion.
And the point I was making was that as WotC determines what is canon and as BG3 has been declared canon, then anything in BG3 is considered to be acceptable to the setting by those in charge of the IP.
Since the line I was responding to was that you cannot make the argument that because it exists in BG3 it is acceptable for the setting. Which is categorically untrue, because of WotC making BG3 canon.
Thus, according to the owners of the IP, everything that is in BG3 is acceptable to them. Hence we can consider everything in BG3 to be acceptable to the setting.
This doesn't make it undisputable, people are well within their rights to argue against anything in BG3 or other canon media. But the argument is there that as BG3 is canon, thus it is acceptable in the setting.