I don't want to jump in on whether or not Mayo is great or not, but the reason a "tackle" is a bad stat is because there is no context.
No data on WHERE the tackle happened, such as 30 yards down field because he was dragged that far, or in the backfield because he had awesome penetration. Or if he has the tackle because everyone else screwed up.
He may have been lucky. He might have a half tackle.
Again, I'm not saying anything either way on Mayo, I'm only responding to why a tackle isn't a stat to get up in arms about. It's far too general, there is no other information except that he was the last man to touch the ball carrier.
I think all individual stats are garbage though, it's a team sport not a popularity contest. I don't agree that QB's should get all the credit for yards after the catch, and I also don't think QBs should get the interception stat against them when a WR runs the wrong route on a timing pass or deflects the ball into the defenders hands. Point is, stats are skewed in many ways, and don't actually mean anything unless you put them side-by-side with the game film and break it down into far more detail.