I think the NFL is witnessing a turning point in how teams will approach QB drafting and development in the future. Need to see much more from Darnold, but if he continues to play well, then it's just one more piece of evidence that QBs need time, good coaching and a modestly competent surround in order to be effective. Goff was considered a bust a couple years ago. Lions didn't do shit with Stafford, but he didn't have much to work with either. I would argue that both QBs would've been fine remaining where they were if they'd simply been given more time and better weapons while they were there.
Mayfield and maybe even Darnold will just add more data to the debate. You have to wonder how much damage is being done to Daniels, Nix and Caleb right now. Daniels was running at the first sign of trouble. That is a bad habit to get into.
Obviously there are exceptions. No amount of time and weapons is going to help Trey Lance, and some QBs like Stroud just don't need it. But I think these are outliers.