Hate is Easy
Anonymity. The age of screen names and generic avatars has enabled thousands of people to prey on and ridicule others without any fear of backlash. Whether it's on social media, an article's comments or something else, those who disagree even slightly with your opinion can blast disgusting language and pure hate in your direction while remaining nameless.
Some of these trolls are genuinely deranged, but others express this hatred because they find it amusing or even fun. It's easy. Hating requires no transparency or investment. The biting remark is sent into the air and there's no chance it will come back to the sender.
The opposite, showing appreciation and genuine kindness is much harder. It requires vulnerability and risk. The other person may not accept the compliment like you anticipate. Maybe your kindness will be rejected for some reason. Showing love may lead to hurt, but defaulting to hate will leave you alone and bitter.