Harbaugh played quarterback in the NFL for 14 seasons. After that he was a college assistant for 7 seasons, coached in the NFL for 2 seasons and was a college head coach for 7 seasons.
The point that's being made about Chip Kelly that you seem to be missing is that Kelly has never set foot in an NFL locker room.
Not as a player, not as a coach.
FWIW, Chip Kelly never played college football.
Do you think that veteran NFL players are just gonna accept as their leader a guy who didn't play college football and never coached in the NFL?