Why can't people just say "greatest of all time" does it really take that long to say? also, it is clear for people who don't know about the Goat thing.
Just the same as any abbreviation I guess, although usually they don't cause such controversy!
Americans love acronyms and acronymify everything... NASA, NASCAR, NATO, job titles, CEO, CFO, CAO, airports, technology, LAN, FTP, SMS, associations, all sorts of things, no wonder acronyms would get their way into emails. ASAP may be the most famous acronym in the world which is probably universally known and a word on its own by this point. My personal favourites are LMAO and GG (Good Game). I think the world is changing and these acronyms are in the wild for decades now, so people who don't get it, it's their problem really. They are living under a rock or something? It's like I recently saw Jeff Goldblum's video and he doesn't know what 5MP means in photography.
The problem sometimes arises when people acronymify song titles on this forum and sometimes you really need to switch on your inner Sherlock Holmes to figure out what it means. But some are already classics like PONO (Planet of New Orleans), SOS (Sultans of Swing), ATRR (All The Roadrunning), STP, RPD and so on.