The "he's throwing to completely wide open receivers" criticism/complaint is so ridiculous. If you go back and watch the All-22, those receivers are open because of Purdy throwing it early, throwing it anticipation, getting the ball to the receiver at the right spot where they have a step on the defense and can just grab it and go. Put a QB that is less gifted in the same spot and suddenly those receivers don't look so open anymore because the ball is arriving late and the defense has caught up and now have an opportunity to make a play on the ball. This is why #1 complaint with Alex Smith, Kaepernick and even Garoppolo who despite his quick release also had a tendency to hold on to the football too long at times.
Watching this offense is like watching those Manning Colts offenses back in the day. Yeah he had great weapons like Marvin Harrison, Reggie Wayne and others but that offense worked as well as it did because the ball was coming out earlier and those receivers looked open as hell constantly because of it. Not that those guys couldn't fight for contested passes but when the quarterback is delivering it early, not only are you in a better position to catch it, you're in a better position to get upfield and start picking up yards after the catch.
Tom Moore was the OC for those Colts teams for a long time and he always used the example of "if we're both going to the airport and you think you know where the airport is and I know exactly where the airport is, which one of us gets there faster?" when discussing the advantage the offense has over the defense. With Manning at QB, the Colts had a skilled professional driver getting them to the airport. Not that I'm saying that Purdy=Manning or whatever other hyperbole but he has a similar quality of anticipation and being able to get the ball out and trust the receiver to be where they are supposed to be rather than needing to visually confirm them first breaking open.
Its not a gimmick, its not luck, its not just a matter of having high end talent, its QB's that are elite in processing and anticipation putting their playmakers in the best possible position to go out and make plays.