Personally I find saying the f word gives my mouth and tongue a pleasant sensation. The louder I say it the better my diaphragm seems to work. In print it doesn't look much different to "folk", maybe even better. Some people struggle with English and suffer mental blocks in expressing their feelings when frustrated, in pain, in pleasure, in anger etc. The f word helps them out.
If it is accepted on Facebook, there must be a reason why it is not offensive on that application.
Once again private pages and groups so they set the standard. ISG owners set the standards here.