The shame Martin talks about is a different shame than the one Hygro talked about, though.
The one is shame out of abuse.
The other out of admiration (or because one just looks bad in comparison to what someone else does - in either case a very different beast, and something that comes from yourself rather than sth that is, in a hostile fashion, forced onto you - unless you just feel bad about it because others witness it, then it is kinda forced onto you, but way softer, still. It is complicated. But I already gave much to work with).
Much like fedoras, describing someone as a "neckbeard" isn't a knock on their slovenly appearance, it's rather a knock on their terrible fashion sense and the concomitant terrible political opinions that would be associated with someone with so little taste that they would think a neckbeard looks good.
It's a shorthand for the reddit intelligentsia.
the OP comic totally misses the point.
Could it perhaps be that it is all that AND what the OP says?
I think you make it too easy for yourself. I think that kneckberd is a host of many different aspects, including the aforementioned mind-set, but also the plain shaming of negative stereo-types in general life-style and appearance. That is the whole deal of kneckberd, IMO. To mix those things into a nasty conglomerate of ultimately taking the accused any legitimacy, regarding the debate and the whole person.
And it really is kind of funny that a feminist would shame someone with a version of "Haha you are just sour because you get no catty cat", while maintaining that he is not entitled to get some. I am not sure that it is really a contradiction. But on some level a slight conflict of values, I think.