That's ostensibly to deter the proliferation of noise and programmatically generated junk where one "artist" might upload hundreds or thousands of tracks in the hope of getting paid due to accidental clicks and the like.

Anyway if the cutbacks only represent 0.5% of the total royalty pool, then they don't impact what's typically meant by the long tail, wherein the smaller back catalog items, in aggregate, end up being a substantial fraction of the total sales.