I got a paper ticket last year...
Hainan airlines PVG-SEA flight was delayed and I missed my SEA-ATL flight on Alaska airlines, rebooked by Alaska rep with Hainan rep help - my Alaska ticket had a "Flight Coupon required" status on it and I had to give them this handwritten copy of the paper ticket for the files.
Not Delta related, but yeah, paper tickets are so rare you really have to stretch...