I solely work remotely and have always done (never worked in an office as such); I always work and worked in bars, coffeeshops, meetup venues: my breaks from coding, managing, negotiations during the day (and often to late evening) are talking with strangers. We end up with ‘keep in touch’ and even sometimes friendships come out of this (it also fixes the ‘you do not make new friends after 30’ thing).
That's my #1 fear now. Life circumstances made me leave the big city I lived in previously, which is also a regional business/tech hub. While I was never doing explicit networking, I got pretty high mileage out of casual encounters and common projects I've done while hanging around a bunch of social and tech communities. Now, I feel totally disconnected, and sans of eventually moving back to some large city, I have no idea how to solve it. "Networking on-line" doesn't seem to be a thing (or maybe I'm not trying hard enough).
(I'm happy with my remote job. Most useful contacts and rewarding relationships I had came from off-job work. It's communities that I miss.)
I've been working remotely from Rome for 5 years with my own startup, and really felt that problem. Sometimes I think about possible solutions for people with this problem (even if I recently moved to London, I'm still not doing quite enough in this respect). Would you like to brainstorm about this, one of these days?