Dweebs maybe?
Well... first let me say that I have no knowledge whatsoever of either REM or Pavement.
That said, a little bit of research tells me that REM were formed in 1980 and their debut album was released in 1983. That's practically a decade ahead of AiC and RATM who are neck and neck to win this poll. Seems logical that REM fandom would skew a bit older. Anecdotally, I can remember RATM being an absolutely massive band when I was a teenager. REM? Not so much. On the flip side I am genuinely surprised by the AiC votes - never would have expected that. In my mind I've always sort of conceptualized them away as some weird half grunge/half hair metal hybrid - file under Guns'N'Roses and Pearl Jam I guess.
Correct me if I'm wrong, but it looks to me like Pavement never had any degree of mainstream success. This is probably their demo but they just don't have the critical mass to break through in this format.
Aphex Twin is a bit different. I feel like much of his popularity is in some way retrospective. I think he benefited a great deal from exposure on platforms like Pitchfork and thus I think his demo may skew slightly younger. It also just seems like electronic music has very few fans on HFBoards in general.
You have to admit that there have been some strange results in these polls. There aren't too many communities where Iron Maiden can beat Michael Jackson in a popularity contest!