I’m probably oversimplifying, but this seems like the first ever mass-migration from one social network to somewhere else motivated by sudden shock rather than sudden popularity. There’s still a network effect, but the primary motivation is not the novelty of something new and exciting. The motivation is to flee a negative situation. Nerds have fled Twitter en masse a few times since 2012. That’s why we have Mastodon. But this seems different. A lot of people are leaving Twitter, and they aren’t just web nerds.