I don't think that most of Beatport's or Bandcamp's catalogue has gone through that clearance process, and I'd wager a large part of Spotify (via tunecore/etc) hasn't either
Nobody has ever given me any crap for the blatant sampling I do from old movies and video games, though I am a nobody and they are always a small (if focal) part of a much larger and original work
But if a song (yours or other people's songs on Beatport/Bandcamp/Spotify) becomes popular enough and it has samples you haven't cleared, expect your door to be knocked on by some of the right holders who are gonna ask you to pay up.
There are plenty of cases of unknown people making songs that become popular overnight and then get stuck in long litigations regarding sample usage. Obviously they're not gonna go after music makers who barely have any listeners.
Nobody has ever given me any crap for the blatant sampling I do from old movies and video games, though I am a nobody and they are always a small (if focal) part of a much larger and original work