People would also downvote if comments were being posted in latin or mandarin on an English language comminity: its unreadable to most of the participants and thereby negatively contributory to the discussion.

We downvote that dude for their obvious attention seeking behavior.

Understandable, since introducing foreign elements into a communication protocol makes it harder to parse.

Same for the gendern movement in german media btw. It doesn't male the language more inclusive but inclusivity more hated by mixing it with something inconvenient.