What should I use it for?
In case of posts - should I downvote things that I don’t agree with? Or things that I don’t want to see in my feed (posts with low amount of votes fell more to the bottom)? Or things that I consider harmful/stupid/younameit?
In case of comments - should I downvote something that I don’t agree with? When should I use this button in case of comments. Or maybe I should not - cause what’s the point, actually?
Absolutely! Answering with a text comment is always better than just voting without commenting. Though voting still isn’t literally without meaning, and still is useful.
Not sure about always. Wouldn’t an attention seeking troll posting something controversial enjoy tons of comments instead of downvotes? I guess a protocol is to upvote your favourite dissent instead of commenting?