Back in the naughties PCLinuxOS was at #1 and people suspected them of cheating. I'm sure some people do try to game it, but there's plenty of organic and bot traffic to compete with.
Besides, I think the popularity thing's kinda backwards - I'd never visit Ubuntu or Fedora because I know what they are, but I'll be clicking on something novel out of curiosity.
Same, I had to ad-block some custom elements on YouTube ages ago because they kept covering the screen with "related videos" whenever I paused to read something.