>>30989562Both are in aid of preventing stagnation. A healthy meta is one that is constantly evolving as people are always searching out new counters to the popular strategies, see pretty much any MOBA. When a strategy becomes so dominant, that the choice is either to play it, and only it, or attempt to find a gimicky counter, then it becomes unhealthy. That's where bans come in.
Tiering and banning are the same thing, Ubers is the banlist for OU, OU is simply the banlist for UU, and so on. (Yes, I realize its more complicated than that, but you get the point). And we saw what happens when you don't do this when mega-ray came out. A tier was founded on only playing 6 mega-rays. It was silly.