Teams blitzed us constantly because our QBs sucked, which worsened the protection of our oline. Smith had his worse season because he didn't get the ball, a result of our QB. Our run game suffered partly because teams didn't respect our pass game, due to our QB. So by solving number 8 you help solve 3, 4, and 5. You are ignoring the fact that a QB will solve more than one problem.
See, now that argument is such a catch-22 because you can argue it the other way just as easily.
The fact is a great QB is NOT going to fix a broken O-line that simply got manhandled all year or had to deal with so many injuries, and a lack of receiver threats. It's also not going to immediately turn average receivers into super wideouts if they can't separate, and run smart routes and if he doesn't have the time to find them.
That all needs to be fixed simultaneously. The fact is we have had a decent QB, in Jake, with a great O line and 2 WR threats as well as a strong run game that got us winning seasons quite a few times.
How many teams with an excellent QB, without those other things in place have reached the playoffs?