Highest rated player according to USCF is 2500+. That doesn't count the FM I know who is 2450+ lives in I believe Grants pass.
http://www.uschess.org/datapage/player-search.php?name=&state=OR&ratingmin=&ratingmax=&order=R&rating=R&mode=FindI did some research, and I guess Nick moved to Washington. Either way, it's probably good to know your top players better.
I agree that to an extent anyone can teach chess. However it should be scrutinized as to how and what they teach. An example is, a 900 can logically only teach the moves and what forks, pins, and skewers are. We use to have a popular 900 rated teacher here. He basically did that. Created several 1200 players in his time. But all he did beyond his own understanding is show tactics books and the kids he had that made 1200 passed him because their natural skill was better. The problem was he would keep them as long as he could. And eventually the players would stagnate and obtain very bad habits.
A chess teacher must understand his limits. And when the player reaches a level where it's better to move on, a good teacher will help them move on. I once trained a player to my level. Once he got there I told him to go find a master. He "did" but shortly after that he became a man and started chasing women. :-) So I don't think he failed, just needs to sow some wild oats a while.
Point is the max you can take someone is to your level. Which is an average of 50-100 points below or above you. Once they reach that, you must admit they are done with you and force them to move on or risk stagnation. If you don't do that .. You are doing them a disservice.