Because you didn’t show any indication that you actually agree with your opponent here (who literally said he wouldn’t bother to look at any sources or links you wanted to share to back up your initial point) because to him anything you said was “just noise" and so instead of recognising that as someone not worth spending time debating with and just going “ok have a nice day" and leaving, you felt the need to self-abnegate as if having the temerity of wanting a discussion with sources is “intellectual vanity" that deserves an apology.

Having seen your similar self flagellating of yourself as a Hectoring White Moderate for being against genocide it appears to me as though your reaction to disagreement on issues like this doesn’t reflect a normal response of “I disagree because of arguments XYZ” or “I see your argument and I’ve changed my mind on the strength of the points you made" but rather a belief that because you’re white you weren’t allowed to have a different perspective or to make a comment which necessitated penance in the form of calling your initial beliefs “intellectual vanity" or “Hectoring White Moderate".

Do you see what I’m saying? Ending up changing your view on the strength of another’s argument I can respect. But this wasn’t even that. It was apologising for having a view at all, to someone who flatly refused to engage in discussion (which was his right but it’s also not requiring of an apology on your behalf).