Also, it’s not like Wikipedia deletes absolutely everything of an account because it’s blocked. If a page is deleted, the delete logs are there (iirc they can’t be modified).
If content from a page is there, attribution requires the page history to be always present.
Take screenshots. Use Internet Archive to prove it. There are so many options that would convince people that at least you tried, that it’s crazy.
Also, it’s not like Wikipedia deletes absolutely everything of an account because it’s blocked. If a page is deleted, the delete logs are there (iirc they can’t be modified). If content from a page is there, attribution requires the page history to be always present.
How dare you expect them to have sources and proof!