I had a few pen pals here and there when I was younger and snail mail was the only cheap way to communicate at a distance. It was OK but didn't usually last long. Most of them just stopped replying, with one or two of them I stopped. I guess we just got bored or ended up too busy with other things. Of course there's no rule that says these things have to go on forever. Dad (very likely an Aspie) had a few pen pals for a couple of decades or so, and got more out of it than I got out of mine. He and his snail-mail buddies were keen on zoology and ornithology so they'd mostly write about that. Some of them visited him eventually - they lived far away so that didn't happen often, but when it did I think it was a big thing for him, and they all seemed like really nice people. One of them lived in Cornwall and we had some great summer holidays there. The guy lived in an idyllic cottage in a tiny village with his wife, loads of natural and fostered kids, and various parrots, cats and dogs. I couldn't believe how calm and relaxed their lifestyle was. Dad might well have developed his writing skills with the penpal thing, and later he started writing lots of articles for small-circulation magazines, mostly about pigeons which he was really into. He was happy doing that and described himself as a big fish in a small pond.
Once the internet got going I moved over to exchanging emails with people, and I draw no big distinction between that and snail mail, except it's quicker and probably cheaper, and much more convenient for sending pictures and sound such as music files. Again, those correspondences rose and fell for much the same reasons. I suppose what with all the snail mail pals, the email pals and various forums such as this one, I've got better at expressing myself through words, though I was never bad at it, and had performed better at English than any other subject at school.