i think ive only downvoted 1 offtopic lame comment so far, on lemmy
its not something i do often
in general the process of downvoting should be reserved to offtopic content, poor quality content etc
on reddit the "norm" was to downvote things you disagree with, which is dumb. then you end up with the echochamber problem and such. I once asked a critical question on /r/conservative and i got banned. Asking questions where the answer make them seem ... dumb, was apparently not acceptable. i got downvoted to hell, and eventually banned. for ONE comment :P