The downside is the cost to communication. I didn't know what a PitM was. After a bit I guessed it was Person, i.e. man in the middle, but I wasn't sure that it didn't mean something else.

I'm not sure how big the gain is here. Are people really going to read "man in the middle" and assume that no woman could ever do this?

Also: where are the people who were offended by "man-in-the-middle"? Can you point to a single non-man who was offended that the evil-doer in this example was identified as a man? Or can you point to a single man who was offended for the same reason?

There are people who object to all gender-neutral uses of "man", probably more from the belief that it perpetuates bias than from personally taking offense.

Well, now you know. And I bet the first time you read 'MitM' you didn't know what it was either.

Right, but learning and memorising multiple terms for the same thing has a cost. Maybe that cost is outweighed by the benefits of making terminology less sexist, that is what I'm unsure about.

Ok, I will bite.

Why is it good? What benefit does it achieve other than confusing people. It is also a good reminder that how things were before. One should not forget the past and things accomplished by many efforts. How is it different than 1984's newspeak or the idea of 'changing the history? Why not choose an approach similar to this (first link I found about Warner Bros' approach): https://twitter.com/stilkov/status/506324544177836032

Can we really label changing "Man in the middle" to "Person in the middle" as "progress"?

Are there other examples of progress that were meaningfully advanced by changing commonly established terminology which was never purposefully offensive?