Honestly, I kinda question how good of a time investment it is to try and allow deletion from the public facing parts of the internet, given the numerous places where your content will be cached or otherwise stored.

There is certainly some value in simply making it as hard as possible to find things you want to delete. Why let perfect be the enemy of good, after all. There's plenty of types of content we certainly want to do our best at deleting even if we can't be perfect. Eg, do you wanna be the one to tell a revenge porn victim, "sorry, we can't make it harder to find the content that harms you because we can't delete all of it anyway"?

But at the same time, development time is limited. Everything is a trade off. We do have to decide what is most important, because we can't do it all immediately. The fact we can't actually delete everything does have to be a factor in this prioritization, too.

There is something to be said about ensuring people know and understand that nothing can truly be 100% deleted once it's posted on the internet. Not that Lemmy is doing good about that, either (especially since deleted comments apparently lie about being deleted).

All this said, I do think federated, reliable deletion is critical for illegal content. Such content needs to be removed quickly and easily from as many places as possible. Without this, instance owners are put at considerable legal risk. This risk poses a threat to the scalability of the Fediverse.