Why do some people heart each and every reply they get on their posts?

Because they appreciate responses

People take the time to answer I appreciate that.

it’s a thank you for contributing to my post. but if i hate your reply i don’t heart it cause i can’t bring myself to

To let people know that I appreciate their taking the time to post. Unless of course it’s a troll or some other form of moron.

Social OCD? I dunno. Ask a question, get feedback, heart instead of actually interacting.

Why not just because, if I reply to the question I normally heart it...