I am not so sure about that. I lose way more matches in 9 ball to lesser players than i do 8 ball. Perhaps its because of the scoring points system in apa 9 ball. They tend to go for broke on hard shots and somethimg falls somewhere and more often than not they are good on their next ball.
I shut out lower levels all the time in 8 ball. Not to say some do not get lucky in 8 ball but no one goes for broke at warp speed in 8 ball like they do 9 ball for fear of making an early 8.
Don't count APA or league games as normal ways to play. Really what you need to do is count wins like a "real" pool match. Especially with how APA counts ball points not game wins. In a real game you can run 8 balls, miss the 9 and lose. In APA you miss the 9 you still win the rack 8 - 2.
Mixing up league scoring in how "hard" a game is or league play with it's handicap systems is not a good comparison. Especially when you talk about your personal matches not what is observed across many games and rules.