LOL.
How in the world can you analyze whether another QB would have played better here or not with the exact circumstances Dak had? It's an impossible task because it deals with the unknown.
What we can ascertain, however, is that Dak hasn't been good enough and that a case can be made that maybe its time to move on and try something different. Maybe the next QB is worse. Maybe he's better. That's the nature of sports. That's the kind of decision making front offices make every single offseason. Most likely, the next QB would be a draft pick so he would likely play worse than Dak initially (as most rookies would) with the upside that he'd eventually be more consistent than Dak, especially in big games.
Dak has had different OCs. Different HCs. Different RBs. Different OL combinations. Different WRs. It's kind of hard to then turn around and make the case that ALL OF THOSE PEOPLE failed, and it was Dak who suffered (and too be fair, in some cases, they did fail him - such as the year Jerry/Stephen made that stupid decision to try WR by committee after Bryant). It's like trying to argue that our 27 years of ineptitude in the postseason isn't the primary fault of Jerry Jones but rather the hundreds of different players, coaches, front officer personnel, etc.
Dak has absolutely had some hurdles/challenges in his time here that are outside his control. But he's also played poorly, at times in big spots, that have little to do with some of the circumstances around him.