Some people here seem to be talking about them as in making actual friends, but it's more in the sense of a friendly party (e.g. followers who have gratitude due to something you've provided for free) rather than the kind of traditional friendship experience we actually have one on one conversations with.
Author here, I think a lot of the examples I made are friends for life!
The projects I started working on with strangers are mostly dead, but I still meet up and spend a lot of time with a handful of them. Even the example I made of Francesco and Fabrizio are of people that met online serendipitously and now have been business partners and friends for almost 10 years
https://twitter.com/search?q=from%3Apatio11%20friend-catcher...
just worth noting.