What if you never upvote or downvoted. I just never think about it, same goes with other social media. Liking post, subscribing to channels or following people just never comes to mind. I just remember the username.
I know what subs I like, so I'll just type the sub in manually. I know what channels on YouTube I like to watch, so I just search for them. I don't have an FB or Twitter or Instagram, mainly cause everyone is, for a lack of a better word, antisocial with their private profiles. So if I forget to follow/sub I can't see their content anyway. Plus it's more inconvenient for me to be bombarded with content from everyone compared to me manually checking it out on my own.
Yes, my front page is made up of the default subs. But I only browse it after I check out all the subs I frequent.