I still don't get why we feel the need to explain ourselves.

One reason is to avoid being accused of editing something that you didn't edit.

If I was debating someone over a topic but I noticed that I made a spelling mistake, I might go back and edit that out because I'm trying to have an intelligent conversation and spelling mistakes annoy me. I will want to say "edit: spelling" so that the person doesn't accuse me of retroactively changing my viewpoint/adjusting my argument to make myself look better and make that person look worse.

If I'm being reasonable in my arguments, but the other person is acting a little crazy and someone calls them out on this, that person could say "I'm not being unreasonable, Avacado is editing all of their comments to make themselves look better!"