Why the rush to floor 100?

I’ve been playing for a bit now and everyone says that floor 100 and higher needs to be rushed for… Why?

I’m still receiving the same loot (I never find legendaries, it seems). Kinda bummed because I would like to be able to contend in pvp but it’s pretty tough with only crafted epics lol

Floor 101, specifically.

For the reason that tier 20 Crystal (obsidian) and Mythstone (elixer) are droppable at that floor onwards but the chances are astronomically small.

Still, astronomically small beats nothing at all, so do Floor 101.