Generally I'd assume those who use things in Ubers are noobs. There's some legendary pokemon that are in OU and in lower tiers but those are generally are the trios and extra legendaries (eg.Mew). A power creep did came around and there was a lot more stronger pokemon that made them seem weaker. Not only that but some regular pokemon made the jump to ubers, Blaziken, Garchomp, and Excadrill to name a few.
TL:DR: Ubers is filled with banned stuff and noobs don't know what the hell tiers are even there for.
Not to my knowledge.