It was certainly a rich source of partners for me when my son was young and I didn't have the time or energy to go out and find them in real life. Actually it was more postal dating, back in the 90s, but it amounts to the same thing.
Basically I can communicate much better through the written word than through the spoken word. I used to take a couple of hours to reply to a letter, to make sure I was saying what I really meant and picking up on the subtle hints they'd written between the lines. When replying to me for the first time, they'd typically say that several guys had written but that I seemed like the most interesting of the bunch.
But I'd be kind of reluctant to go back to it. It always seemed pretty obvious that we were getting together with a view to becoming sexual partners, which sometimes felt acutely embarrassing. Everybody else got ignored too quickly, because once I know somebody's interested in me, I just gravitate to them, even if I don't know them very well. Next thing, I've got a fully-fledged relationship with somebody I don't really know, which is great for dealing with my loneliness, but it also means that I'm completely at the mercy of somebody who could turn out to be a destructive jerk. In some ways I'm happier just making friends with women gradually in real life, so that I've got the time to see what they're made of before I put my neck on the block for them. It's nothing like so easy that way, but maybe it's a wiser approach.