The higher-score comments there don’t seem to be particularly hostile to Lemmy. They talk about legitimate concerns like whether Lemmy as it exists now could deal with a Reddit-size volume of data, The top comment at this time speaks favorably of !selfhosted@lemmy.world.
Of course people who are still using Reddit are more likely to view Reddit as favorable or acceptable and alternatives as problematic, or not quite there yet. I’m actively Fediverse-first in my use of social media, but I still end up on Reddit quite a bit for niche interests because that’s where the most people are.
It seems to me software designed to facilitate discussion shouldn’t have a downvote buttton. There should be a UI for marking comments as inappropriate, but it should require a second step saying why. Perhaps one of the reasons should even be “I disagree”, but that option should have no effect.
It’s not impossible to abuse of course, but it nudges people in the right direction. Those UI nudges can be pretty effective.