I've never walked up to buy a ticket, but don't you still have to go through the tapstiles? Several years ago I had will-call tickets and I remember queuing to pick up the tickets, and then queuing again to go through the tapstiles. The issue isn't the ticket or the ticket window, but that the tapstiles now require both a ticket and a park reservation, which in turn requires an MDE account.
I suspect that if somebody walked up to the window without an MDE account or smart phone, the CM would find a way to help that person -- most likely by helping them create an MDE account, link the ticket and make a park reservation.