Are you seeing users with most of their comments at +/-0, or do you mean you see -1 on all their posts? I’m pretty sure there is a setting to have your own comments not automatically be upvoted by yourself. The users you have seen might just have had that turned on? Resulting in 0 for all their comments unless someone else upvotes it.

There was a similar question a while ago with some nice reads in the answers :)

https://lemmy.ml/post/17575792