Comment upvotes works both ways and due to the monetisation of content on Hive, people are also concern on their reputation here.
You can just spam comments on Youtube, writing crap and nothing happens. Try that here and you won't last very long. So content is very important, but your reputation is even more so.
Except that the channel owners may mute/ban you. Some channels even have pre-moderation, which means that they check your comment, before (if) they let it out. Spam is not welcomed nowhere.