Yep. That's why you sometimes see people downvoted into oblivion, simply for stating something which is true, within a community that is deluded about that given thing.

But at the same time, saying it is truly pointless, would mean you also consider the very concept of democracy, pointless. Yes, there will be a percentage of people who are unable to form a level opinion, and how many such users there are can vary wildly depending on who sees a given post/comment in the first place.

But results speak for themselves. Reddit's voting system does work. Especially because when you go to a specific subreddit, its about a specific subject. Meaning the users who are there, likely align in what they are interested in, meaning the voting is now a much more accurate representation of what the subscribers of a given sub want to see. Your subjective opinion is likely to match that of the users looking at the same subreddit. And this continues working even as you subscribe to multiple subs. Each post only gets shown to users who subbed (unless on r/all), even though each user has a mixed feed of the stuff they subbed to.