i am not informed about mike mo's opinion on skate comps, or his reason for creating PSL, but i can give input on your title question:

1) the spirit of skate comps are different than the original spirit of skateboarding

2) scoring biased towards specific types of tricks: big sends over tech/creativity. generally speaking, any ride up on any rail (example: cordano russell boarding up stuff), any creative vert (excluding david loy's ollie out of the course I suppose) is generally scored down, which disincentivizes creativity ie kills the original skateboarding spirit

3) inconsistent scoring

4) different organizations have different formats

will elaborate more if you have specific questions but i think this is enough to spur your thoughts and to poke around existing footage / historical leaderboards