The magic the gathering subreddit has to moderate out the word "proxy" or risk getting banned. seems plausable like there are just a lot of speicfic rules you gotta follow to be a subreddit
I can track down the actualy post if you want
I don't recall there being a specific announcment, but the logic goes something like this most people who use proxy are referring to fake magic cards printed to look like real ones and therefore talking about proxies how to make copies etc will lead to people cheating or stealing.
For what its worth i used the term proxy for a decade almost exclusively to mean a cheap paper copy of a magic card (or even just writing the word on a sheet of paper and sticking it in a sleeve over a land) and I find this restriction wrong-headed.