Here is the thing though: if there is a good enough guy hanging around later in the first round (which is where I think the expect to draft), the Browns wouldn't have to have the guy start immediately. While I think it's best for a QB to learn on the job, I think it's better to give the guy at least a half a season before they have to start.
If you look over the past twenty years, I think it's easier to win a Super Bowl with an elite QB and a lesser cast than it is to win a Super Bowl with an amazing team and a decent QB. The game is just so dependent now on QB play that they can make a big difference.
The Cardinals improvement so far is two fold: The supporting cast is better, but Murray has reached the level that a lot of us thought he could get to. He is almost to the point that he is a QB that could win with only two good receivers and a bunch of ok players. Mayfield is the type of QB that for him to match Murray's performance, he needs a top five OL, a top five RB corps, and good receivers. That's hard to maintain for the long haul.