Yep, users and communities can shift away to a new instance if they want. While the fact that there might be 3+ communities on different instances all covering the same topic is a weak point, it’s also a strength in this regard, so it kind of evens out. And if you really want to, you can make your own instance.
Reminds me of how RTGame censors the word ‘fuck’ with the word ‘Youtube’ on videos posted to Youtube