What Use Is An F-call?

What use is an F-call? The radio waves are open to all comers, licensed or not. That means that while you have to be licensed to use a particular frequency and that stiff penalties apply if you're not, there's nothing physically stopping anyone from using any frequency. I recently had a report from a fellow amateur who had a particularly unpleasant experience on-air. They were accosted by another station. Fortunately that amateur had a witness to the experience, so they didn't feel completely alone in the moment. It did stop them from being on-air until surrounded by friends. This discovery brought out other experiences from other amateurs, one told how another station was impersonating their callsign, and only being advised of this by other amateurs brought this to their attention. I've heard another station use my voice from a recording like the news, and transmit that on a local repeater, and I've heard other stations being abused and stories about abuse. Abuse will happen. Idiots are everywhere in soc