"fear uncertainty and doubt" is a phrase I may have encountered once per year. Makes zero sense I have to Google shit all the time for a single use per year. I'm not going to remember something so utterly pointless and useless
It may help if you think of it like any old-timey slang. You don't use it more than once a year, but when IBM/MS/ORACLE/CISCO were using those tactics against open source in the earlier days of the public internet - It was used a lot.
With lemmy being somewhat skewed towards the technically-minded, and older crowd, it is something we used as a general word often enough that to a lot of us it is just another word, and not an obscure abbreviation/initialism.