The instance doesn't need to be blocked when it defederates itself with the rest of the fediverse. Regardless, it's important to highlight the content that the Lemmy Developers are happy with
Both of these instances have already defederated themselves. You're on a community that is dedicated to highlighting hate-speech and tankie behaviour.
and yes, they have tried to impose them on other instances. Even the Developers themselves tried to force their beliefs until the developers of Kbin told them off.