People are forgetting that Purdy is a rookie. He should improve at reading NFL defences as he gets more experience, which will help any QB's game overall. And he is actually quite dangerous with his legs - he's hard to sack, with good escapability, and when he does run, he picks his spots well and can go for big gains. He's got good football speed too, even if his combine speed is nothing special. I am not sure why he gets dumped on. The 49s cannot afford a huge QB contract with how much cap space they have allocated to other positions. Purdy is on a dirt cheap contract for quite some time, as a 7th round pick, and will lets the 49ers get away with their roster building model. Purdy is about as ideal a fit as you can get for them.
Can you win a Super Bowl with Purdy? Is the 49ers approach of going with a good-but-not-great QB that cannot really make the "wow" throws, and stacking the roster elsewhere, feasible? I think it is. Having a special QB is a huge advantage, but there are only so many of those go to around.
The real problem the 49ers have had - heck, that most of the NFL has had - is not that their QB is precluding the possibility of Super Bowl wins. It's up against Patrick Mahomes. He's the best of all-time. I don't think it's debatable anymore. When you pair him with Andy Reid and that very stout Chiefs defence, you need a special QB to beat him IMO.