Snail mail is social contact, not social media. Just like calling your mom on the telephone is not social media.

No. My father friend used to be part of chess-over-mail society. He was participating in several competitions at the same time, and periodically was getting all country as well as regional bulletin on competition states, progress, tidbits etc. I was very fascinated by this whole setup...

And I heard as well that stamp collectors and coin collectors societies worked in the same way, bulletins, regional, all-country, exchanges etc.

All industries whose markets measure in the billions of dollars appear only with computers.

well, that might be true, if we measure social media in money