I'm not in a fighting mood today at all but just want to attempt to clarify a tiny bit if i may:
I do not think the story is or was hidden / covered up by socialists in general, or by you or anyone else here.
I do think that the story was repressed at the outset by the powers that be in Germany for fear of it stoking civil unrest / right wing reaction.
I also think that in the weeks that followed many people made the mistake of thinking that the best way to stop this playing into the hands of the far right would be to refuse to discuss any explanation of what happened that placed weight on the issue of where the alleged perpetrators came from - so that anything that you might call a ‘cultural’ attempt to understand what happened, particularly with ref to the sexual assaults - became restricted to the right wing press and people with anti-islam / anti-immigrant agendas to push.
So anyone who wanted to talk about how this mob sexual assault was different, in important ways, from types of sexual assault we are familiar with in Europe (Birmingham on a Saturday night, Oktoberfest, whatever) was doing something morally objectionable and was probably a racist.
This desire to not allow the origin of the perpetrators to be a part of the conversation was, I think, well intentioned but dishonest and cowardly. It often looked like a downplaying of the mob sexual assaults, because it involved attempting to say that this is not really anything out of the ordinary, that nothing new was going on really etc.
I still haven’t got a clue why so many men got together in a big group to sexually assault women, instead of just stealing from them, but I wanted to do was try to guess at how come this horrible thing happened, what made it possible, look for parallels to help make sense of it, because having no explanation at all for such a phenomenon makes it much more scary.