That is inaccurate, all that matters is that Personally Identifiable Information (PII) is gone. A provider has no obligation to delete any data/content if it doesn’t identify you personally. So, assuming your instance requires an email address (which some do, but not all, so clearly Lemmy allows to operate without it), or stuff like real name, phone number, etc (but I’m pretty sure no Lemmy instance requires that), all an admin would have to do to be in compliance would be to overwrite those PII fields with anonymous information, and they’d be in compliance. No records actually need to be deleted.

Source: I’m not a compliance expert, but I’m a software engineer who worked for some of the most major companies providing online services, at the time GDPR passed. They all spent many millions to align to GDPR because for some of them the liability would have been in the hundreds of millions of dollars, so they took it very seriously. Yet, of those that were soft-deleting records like that (with a Boolean), none of them stopped doing it. All of the efforts were around cleaning out the PII only.