None of these recruiting guys want to put their career on the line to call Arch straight up.
1) Most important: They depend on access to the Manning family, and the access that an alliance with the Mannings provides for their careers going forward. Manning Passing Academy, all the coaches and former players that are in all aspects of football culture. They are kissing the ring.
2) It is good for business that he is #1. It drives clicks, it drove a lot of discussion, now it is driving debates.
3) The pedigree. Knowing what we all know about the Mannings, are you really going to go against the grain and put all your chips on the table for one recruit? You won't get dinged for being high on a guy(s) that flames out, busts happen all the time. You will be immortalized if you criticize a Manning and they go on to do great things. It would be one of the most obvious guarantees in football history that the next Manning would be the next great QB, if you're looking back after his however many Super Bowls with the benefit of hindsight -- which is how sports journalism and social media culture works now by the way.
The only people that are zigging are guys looking to make a name for themselves, and even if they are right, they are going to make a career and beat their chest about the one time they were right that a Manning wouldn't be the next great QB? The Mannings will hate you forever, everyone that loves them will hate you forever, other members of sports media will roll their eyes at you. It's not going to earn rep or respect in the football world. Think of how many coaching trees or former players think highly of the Mannings, or think that they owe some of their success to the Mannings. You won't have many allies. So even if you are right, you can't hang your hat on it.
I am not saying that I appreciate the approach, or that I would do the same thing. I am saying that I understand why this is playing out like it is, even if we all know what's really going on. People want to tell it like it is, be honest, call things how they are. The reality is, that like most things, there is more nuance and long-term strategy involved.