This isn't like tiktok where "the algorithm" will pick up on your dislikes and stop showing you that content. Your downvotes nerf the visibility of that content for everyone, while not actually reducing its prevalence in your feed.
The opposite, when the anime stuff I post gets downvotes, I double down on posting more. So unless you block the community, the content will appear in your feed again.
Mods can't see votes yet, but once I can, I would totally do this. Admins already can.
If you're just downvoting every post in a community or on an instance, you're basically engaging in content suppression. You are actively reducing the visibility of an entire type of content which someone does want to see and engage with. But you're tapping the brakes on that content thriving on lemmy, while doing nothing to actually personalise your feed.
You don't get to gatekeep what types of communities get to be on the fediverse. That's up to admins, and the only limits even they should be enforcing are legal and moral.
If you just don't like the content, why would you keep downvoting it instead of blocking it?
Downvoting is for misinformation, for posts that don't belong in a given community, and comments that are in bad taste. Kinda like this post.
If something just isn't for you, downvoting it is like trying to stop other people from listening to their favourite music because you don't get it.