True, but Josh has that too. The surrounding parts made it tick for the Chiefs and kept them in the game whilst Mahomes worked it out. More often than not, particularly post season, Josh doesn't have that luxury.
EDIT - My original reply was stupidly petulant so I'm going to edit. I think 31 teams would trade for Mahomes now. I think 30 would trade for Josh. But if the question is would I could go back, keep draft position in 2017 and pick a raw Mahomes or continue, trade, and pick a raw Josh in 2018, knowing what we know, I would still go for the latter.
I think Mahomes would have struggled more to learn and grow under the coaching and roster in the early days in Buffalo than Josh did. I don't think temperament wouldn't have suited the scenario he found himself in - look at the almighty sulk after the regular season game this year. I don't think he would have got to this point under McDermott; my belief is he would have looked worse than Josh because, IMO, Josh's ceiling is higher and his 'superman' mode can overcome deficiencies which even Mahomes can not. The issue is the floor - Mahomes, when struggling, does not go as low as Josh can. I also think Mahomes is better at reading the field. I appreciate zow2's argument that Josh is the better football player but Mahomes the better QB. But because of temperament and mentality, I would not still not change anything in 2017/2018 drafts when it comes to the QB pick.