So why does Smogon ban things from Ubers? isn't it supposed to be, first and foremost be a banlist?

And no this isn't a "let's hate Smogon thread", I actually don't mind them, I'm just wondering why they ban things from the supposed banlist?

I mean I guess it's to make Ubers playable without total bullshit here and there, which I guess I understand; but the way I see it, if you're going to play the banlist tier, expect shit that's banned from the the other tiers. That makes sense right?