I’m not always good about this, but I see reactions, or even written gratitude, as a way to incentivize great posting. If somebody made something I enjoy, or made me have fun, or laugh, I feel that I should let them know they did a great job. I think that not only encourages them to post more great content, but is a more human approach to the internet.
In real life, after all, if someone says something funny, you’ll instantly catch smiles and laughs, and an overall great atmosphere. I think the more human and natural things are, the more everyone has fun.