Oh my word, I'm truly sorry that exposure to that type of callous thing has had such a draining effect on you Leslie, you're inherently entitled to better. The links you provided read like the work of Elliot Rodgers in that it's the mirror of his suggestion that a small proportion of women be allowed to survive in concentration camps.
Having said that, I expect this type of thing gets so much attention due to the sensationalism bringing in advertisement revenue for media sites. Similarly, I expect there's questionable political pressure to focus on the infinitesimal minority of objectionable feminists advocating such vile notions since it legitimises the way in which much of society dismisses and defames them as a whole. Personally, I see these people as reprehensible but don't expect every other feminist to account for extremists. It's somewhat similar to the way I don't expect all Muslims to constantly disavow extremist Islamists. It's unfair of me to generalise in the first place and simply drains energy from minorities by making them loop through conditional hoops to be seen as legitimate.
With regard to 'killallmen,' I was under the impression that it was originally created by trolls from a politics board on 4chan to try to discredit feminists in the same way that they had masqueraded as women of colour or trans women in order to start horrific hashtags that they could then use to discredit activists. Somewhat similar to them starting the myth about a 'free bleeding' movement. Is that not the case? Oh dear if that wasn't the case.

As for ironic 'misandry,' I would never engage in it personally but I have feminist friends that do sometimes. I somewhat dislike it for precisely the reasons outlined in the opening post but, at the same time, I also see it as very loosely akin to gay people generalising straight people, trans people generalising cis people, or black people generalising white people. Of course, each of those isn't equal in its uses or emotional roots but I tend to think the underlying purpose is fundamentally somewhat similar. By generalising, I think such people are attacking the overarching notion of their
oppressor class rather than judging every individual member of it. For me, it allows the oppressed to crystallise the oppressor in their mind, unify behind that notion, and purge stress by sharing negative emotions when they're presented with a particularly odious little twerp. It seems to help my friends' distress so I tend not to object to it because they've repeatedly made it clear that it's not really applicable to every individual in the group, just the concept of the class itself. If I knew they had trans friends that were being hurt by it then I'd immediately talk with them and will probably have a discussion to at least let them factor into their considerations anyway since my hypothetical worry has been shown to actually happen by the opening post.