No, there was a period of time on Tumblr where you could actually edit other people’s posts when you reblogged them. The edit would only appear in your chain of posts (i.e., your reblog and if anybody reblogged your edited version), but it would be completely indistinguishable from the original unless somebody went and viewed the original post on the op’s blog or something. No quotes or acreenshots needed. Simply hit reblog, scroll up, and change the original post however you like, then hit post.