Yeah, because he went 1st overall LMAO. While things could change, Murray is more of a late 1st round pick at this point. His signing bonus in that range would be nowhere near $20+ million, in fact it would be in the ~$5-7 mill range which isn't drastically more than what the A's gave him. As a late first round pick, he'd be going to a team that would be "grooming" him to start...ie: he'd be a backup most likely. Is it better than being in the minors? Sure, but lets not pretend like he signs his contract and he's a day one starting NFL QB.
Murray is even smaller than Mayfield and he has nowhere near the track-record of performance that Mayfield did. There is a BIG difference there. Murray has one year of performance, and NFL teams typically weigh that as pretty important in evaluation. Kyler Murray was NOT good in his other most-relevant season of play at Texas A&M.
Mayfield: 45 career starts, 1497 career pass attempts
Murray: 17 career starts, 519 career pass attempts