Are you using "affine" to mean "for which one has an affinity"? I have never heard that nor can I see that as a wide-spread definition. Just curious!
I was wondering. Maybe "refined", as a derivative of the verb?
I think that poster is saying that here on HN posters typically preserve points, lines and parallelism. Rude, quite honestly.
Maybe non native speaker, here in germany we often say "technisch affin" which means proficient with technology