As in your brain on drugs = scrambled eggs.
At a small business, designer has a document fancily laid out in an expensive proprietary desktop publishing application. Editor needs to make substantial edits throughout the document, but does not have a copy of the desktop publishing application, so prints out a copy of document, marks up edits with pen, hands to designer to transcribe (with errors, of course).
Had this business used free software, editor would have simply installed the desktop publishing application.
I had completely forgotten this simple case for free software, probably because I haven’t touched a desktop publishing or other specialized document creation application in years; I just happened to overhear a conversation relating the above situation, without reference to the irony of collaboration using closed software devolving to printout, pen, and data entry.