what's your take on employers banning the use of languages other than English between coworkers at the workplace?

https://linux.community/post/3497784

It is a sign that they have an unhealthy need to control others and it is best to get everyone to quit collectively
Counterpoint: In the Airline Industry, Aviation English is the lingua franca, do you think pilots and ATC should quit over the language requirement?

That is not a single boss but an industry wide standard, like using metric vs imperial units. There is no market corrective mechanism in that case and thus quitting would be pointless.

But excellent point.

Another example would be requiring code to be written in Java or COBOL.