I said with exceptions for a reason.
I know how champs are discounted, and part of choosing which non 6300 to discount is ease of play.
I also commented that there is room to reach a skill cap on some of them - alistar being specifically who i was thinking of. You can get really good with him, hence why he shows up in the pro scene.
Simultaneously though, alistar has so much peel that even an inexperienced player can make him useful. Tristana is all point and click. Garen has easy sustain and tankiness. Annie is point and click. Master yi just farms the jungle. Nunu has a straightforward teaching mechanism in his consume. Most 450ip champs have pretty straightforward playstyles and for good reasons - they're the ones most new players will try to pick up early on and have an easy learning curve. That doesn't mean a challenger Annie can't wreck face, just that a beginner Annie can do quite well.