I delete a lot of the comments submitted here. For some postings, the majority of submitted comments get deleted. I don’t delete comments because the commenter disagrees with me, actually comments agreeing with me are deleted far more often than ones that disagree with me. The overall goal is to try and maintain a comment section worth reading, so comments should ideally be well-informed and tell us something true that we didn’t already know.
The most common reason for deleting a comment is that it’s off-topic. Often people are inspired by something in a posting to start discussing something else that interests them and that they feel is likely to interest others here. Unfortunately I have neither the time nor inclination to take on the thankless job of running a general discussion forum here.