Leaving a comment feels weird, too. There's not even an OP to talk to, so it's like shouting into the void.
In principle, I do get the need for these communities. Like, if you just want capybara pictures to show up in your feed, then you don't need many comments on those.
But these bots usually spit out far too many posts for my liking, so more often than not, I do block them anyways.