The thing with Mayo is that he hasn’t even been coaching that long. The Patriots still have won 3 of the last 5 AFC championships and he wasn’t a coach for any of them. 2 years as a position coach and you’re in line for a head job? That doesn’t make an ounce of sense.
It does make sense if you consider;
a) Teams constantly fall over themselves to hire a Belichick disciple. Brian Flores got a head coaching gig after a very similar path. 2 years as a linebacker coach and then was "defensive playcaller" in 2019 before getting the Dolphins job. Never once sniffed a more important role though he was around the Pats for a decade unlike Mayo. At this point grabbing coffee for Belichick means some team will probably at least interview you for a job.
b) Teams refuse to learn from others mistakes. The Belichick coaching tree is rotten and yet somehow it goes ignored and each team that is next in line goes "No, THIS guy is the one to break the trend!" Or if you're extra stupid, you hire a Belichick crony already fired and go "i can fix him!" like the Bears look like they're about to do with Brian Flores.
It's lunacy.