It’s a saying - it just rhymes better than “explanation is not justifying.” You know what I meant. I gave an explanation for why some people do what they do, and you responded as if I were justifying it, which I wasn’t.
Had you used the word excuse, that would at least suggest I acknowledge something is bad but am still okay with it - which would be closer to how I actually feel about it. But saying I’m justifying it implies I think it’s right, reasonable, or morally acceptable, which completely misrepresents both my view and the intention of my post.