I suppose if the coach has been involved for years in the league...
He would know who the good players are, and wouldn't need the tryout.
Someone new to the league would be at a disadvantage. League leadership should know that and help out or devise a more fair or random way of dividing teams.
Kids tanking the tryout could happen with no involvement by adults.
You make good points. But I wouldn't bring it up with the league. Until maybe after the season.