I don’t know about the mental health aspect, but I know that up/down-voting can be abused. Getting rid of down-voting doesn’t really fix anything. For me, on lemmy.one, which also has down-voting disabled, it just kind of makes me feel like I’m supposed to up-vote everything I don’t dislike. So it seems like disabling down-voting just breaks an otherwise useful metric. I think an actual solution might involve weighing up and down votes according to a karma-like score of whoever is voting. This way, it will be very inefficient if a bunch of fake or bad accounts try to harass someone with lots of down-voting or try to promote a bad post with lots of up-voting.