You clearly don't understand how autistic girls minds work, or any insecure woman. Mikasa is how they believe they are, they think their autism in real life is "cute". Mikasa getting Eren means they don't need to improve themselves or they can keep dreaming competition doesn't exists.
Mikasa x Eren = victory for them.
Notice how when someone posts Eren x Historia or Eren x Pieck a post trying to make them feel guilty appears>"you selfinsert as Eren to fuck girls who can actually talk normal unlike me!"
Let's be honest, Erenfags ship EH, that makes EMfags (Mikasa selfinserters) mad because it brings them bad memories from their real lives aka "The boy I like/Eren would choose a different girl, not me" so they start "torturing" those evil white males for rejecting their selfinsert (Mikasa). Notice how they don't seethe against that Eren x Gabi posting, probably because they are the ones posting it because their enemy are Erenfags, not Eren. Eren is their prize. This strategy is also used by modern feminism in real life>"I'll try to make those who rejected me look bad at the eyes of the world(4chan in this case)"
This is also used by one Eren x Armin fag aka lgbt supporter. Insecure people can't forgive being rejected and they are usually the most twisted. Gays have the same sense of humour as women (bad), you can see that homosexual not even hiding his Eren x Gabi posts using that DMCV character, or maybe he forgot to hide it because he has a big ego and low intelligence