back in the early 00s I used to do AOL tech support. Even then a lot of people were on cable or DSL. Vast majority of calls we got were from people out in the boonies or the elderly so it doesn't surprise me that there are still a good chunk of people on dialup.
Actually by that point most of our calls weren't even for Dial Up. the thing with AOL support back then was if the user also had other computer issues unrelated to AOL that they brought up while on the line with us we HAD to address them and try to do support for it. Callers would discover this fact and use AOL tech support as a defacto go to tech support for ALL computer issues. They'd start off with some random easy to fix (they knew how to fix) dialup issue and then would say "oh wow you fixed it, I wish you could also help me with this problem I've been having for awhile with..." and yup, we'd roll our eyes and say "oh, what what's wrong?" A good chunk of my calls, believe it or not, would be for printer issues.