I am the administrator of:
I administrate a PeerTube instance (peertube.wtf) and everything is just much more complicated compared to a Lemmy instance.
One reason I don’t “auto-federate” is because there’s a ton of pirated and questionable content. So much content is in a foreign language and so many instances are inactive and therefore filled with spam.
That’s why I add instances manually to federate with. This way, the quality of the content is also much higher.
When posting or saying something in public, there’s no way to retract it.
There’s no difference from posting something on “the Fediverse” or Reddit. Just because you delete your post, does not guarantee that it’s gone. Reddit most likely keep a copy of it anyway and there’s sites that save everything that’s posted on Reddit. so the “issue” is not exclusive to Lemmy.
What you want to aim for is anonymity.