Wouldn't every viewed copy anywhere then be a saved copy of the original post? Does that distinction even mean anything when it's still posting specifically to the original instance?
If I reply in a Lemmy.world thread, I'm still posting on Lemmy.world even if I'm viewing from Kbin.social.
As a comparative example to old and dying social media, it would be like finding a link to a celebrity's Twitter comment on Reddit and you saying you saw the person saying that on Reddit, which would be extremely misleading to anyone listening, thinking that the celebrity had posted it on Reddit.