ah apologies, I'm not sure why I didn't read that correctly the first time. It's wrong to call it "extremely negative" though, my words were "pretty bad". There are 2 levels lower than MM but they're rarely used.

MM is a warning—it means you need to improve or you'll likely be put on a PIP.

No worries! I apologise for misrepresenting it as "extremely negative", still with the meaning of "pretty bad" I believe it's a specially disgusting type of language, why use positive-sounding jargon for "underperforming"? What's wrong with using "underperfoming" if that's what "meets most" means?

I despise this, the dissonance between a positivity-sounding "meets most" with the actual meaning being "pretty bad" is what I expect from the North Korean regime, or Russia. It's a disgusting type of newspeak/corporatespeak which, admittedly irrationally, boils my blood.

There actually is a reason (though you might not like it). The internal docs are pretty open about this, I think I can do a decent job capturing the idea:

The idea is they consider themselves to have a very high bar (which I think is largely accurate). They say you “meet most expectations” which means you hit the marks on all but 1 or 2 criteria. It’s not that you’re not good at your job, it’s that that’s not good enough for them.

Of course anyone receiving a MM is having a very shitty day despite that. They could use more direct language but I’m not sure it would have any practical difference.