They don't prioritize finding historical data, which is why the permalink URL is all the more important. There are (or at least were) third-party services dedic

They don't prioritize finding historical data, which is why the permalink URL is all the more important. There are (or at least were) third-party services dedicated solely to finding older Twitter data. Again, this is no different than any web resource. We even have an HTTP header specifically to indicate content has been deleted.