This has sort of happened in some spaces - in certain right-wing communities Twitter has been largely replaced by Gab, Patreon by the aptly named Hatreon, etc.

The issue becomes more severe when it runs up against services that are hard or expensive to start or which rely on other uncooperative services - look at what's happened with Daily Stormer and Bulletproof.ai for example - Bulletproof wants to provide them service, but they're unable to find a TLD thus far which will allow their domain to stay online.