And you don't see the obvious link between people saying RTFM! because someone didn't read the manual, and people saying "RTFA" or "it's in TFA" because people are writing comments on an article when they clearly didn't read it?

These acronyms are born out of frustration and not cordial conversation. Again using "fine" instead of "fucking" is just a euphemism. It is not the original nor correct phrase, and it doesn't make sense for it to be anything other than "fucking".