Your first point, quite, but you don't expect that to happen in elite football (and by that I mean probably as far down as halfway in League 1, and certainly anywhere Brighton would loan out to).I'm aware of cases in other sports of players being ruined by bad coaching. It's possibly difficult to transfer those examples to football, but when bringing a young player through and developing them I'm sure you can add or subtract a few months to how they come along depending on how you handle them.
The management/personality side will be more important, but that's so unique to each case I don't see any point in citing prior examples.
I do love the human capacity to see patterns where none exists, though. And I plead 'guilty' to doing that myself