Well, you had Lisp structure editors already in the 60s. Doing it graphically doesn't really add too much to it. If you read the manual for BBN Lisp, you can see that it did end 60s / early 70s more than many current systems do - like managing source code, working with images, structure editors for code and data, sophisticated user-level error handling, etc..
You surely could not display inline structured data and interact with it graphically on an IBM 704 teletype.