The ad hominem was "doesn't get HN in the first place". It's very dismissive of people who disagree with you. And it's not the first time you've responded like this.
>>lmm+(OP)
Oh, I see now. Sorry about that. Normally I'd delete it, but in this case I suppose I'd better leave it in.
I still don't see any ad hominem, and as a statement of HN's very specific values it seems obvious to me, but you're right that I shouldn't have said it in a dismissive way.