As a writer, I like to see comments come in, and votes in a poll would feel relatively lifeless.
This is true for the polls. I turned off poll notifications a while ago, and if I didn't get curious every now and then, I wouldn't ever know how many votes they're getting, whereas comments always pop up via email/notifications.

I think I'd prefer silence to knowing that people liked the story but not enough to bother typing a few words.
Most reader I know who like the polls don't cite this as reasons for not leaving comments. Part of the time, yes, it's not true - but a lot of people deal with staggering social anxiety that extends even into online settings, so a poll is the more comfortable way to go for them. And I've seen others who are tired of seeing authors complaining about the kind of feedback they get, so a poll kind of takes it out of their hands (I can only complain about how I wrote the poll, in other words, and not how others responded to it).

And yes, most authors I know love getting comments, no matter how old the fic or what fic it is, but even knowing that it can be difficult to respond.