I'll chime in a bit.
MTFs on Reddit really love to do this a lot. I believe that's where it likely originated. The entire premise revolves around, basically, all FTMs are women and always will be, and to MTFs generally, they believe FTMs have it far easier when it comes to the two sides of being trans, and so the MTFTM people love to exploit and prey on people they perceive to be women (FTMs) in order to be seen as real women while also still having a firm grip on the trans label and remaining in the community without being associated with anything male/penis having. It also allows for easier assimilation into lesbian spaces if you tell everyone you're just some FTM and not a man in a dress that feels like a hot anime yuri lesbian like all those other gross transes.
Which is nothing new at all for these guys really, and it really is just expected of them for them to feel quite comfortable with harming anybody who owns a vagina (when they don't and never will).