Without getting into several issues regarding being a walk on first, if you’re not receiving athletic money the coach doesn’t have any skin in the game. The coach has everything to gain and nothing to lose. Second, about 18-20 players receive enough playing time to be considered contributors. Where do you believe players 28-35 sit in that equation? The goal isn’t to get rostered. Chances are if the player doesn’t quickly move up to the 18-20 he will leave the team or get caught from behind by new recruits in following years. The goal should be to get on the field.
This said I’ll cite two examples. A friend was told by his son about twenty players arrived in the fall bragging they were preferred walk ons. The only preference they got was competing for three roster spots.
In the second situation one of my son’s college teammates was a late bloomer pitcher. He walked on. He’s now pitching in the majors. He went from walk on to one of the top ten pitchers on the team his freshman year.