It's not about who have the power. There are still mods on piefed with all the same power as lemmy mods.
But with the downvoting penalty people get an opportunity to banish people they do not agree with to the shadow realm in a way that's not possible in Lemmy. It's not the power of the people it's the power of a furious mob against anyone out of the mob.
You say "hideous user" I say any user who disagrees on the slightest with the mob ideas. And as the echo chamber closes smaller and smaller divergences will get punished until people will literally just be an echo of the allowed discourse.
I do think those piefed feature are a great mistake. People still have all the power via blocking users or instances here. But the "extra power" to the people is not really that, is just a net of authoritarianism in disguise. Heavy punishments to anyone disagreeing with authority, it doesn't matter that much if authority comes from a King, an aristocracy or a Soviet (assembly of people) it's still authoritarianism. And that's what I think will happen with any piefed instance that enables these features.
We all know that no only "hideous users" get downvoted, and that "hideous users" not always get downvoted. We all know that even the platform says to not use the downvote as a "I disagree button" people use it for this.
I'm more on the opposite side of the spectrum on this matter. And more and more I think it's better to completely get rid of the downvote button. If you really don't like something block it for you, there's no need for people to have tools that greatly affect other people. For instance if you downvoted some comment of a third user and that comment gets hidden. I may like that comment but now I don't see it because you were given a tool that gives you power over me. A tool like that is great for majorities to oppress minorities. As part of several minorities I've always been wary of those.