So even if you don't want to do the ID thing, there are alternatives that you see all over the place (like venmo) Have a rotating QR code seeded with a unique to the user id. Then with ticket master, require a login to buy tickets. Register the tickets to the ID and then do the lookup with a combination of the ticket id, rotating qr code, and the user id.
That requires the admitter device to send the challenge back to HQ, but that shouldn't really be much of a challenge. Tickets then become linked to the user's account (perhaps you allow transfer).
This is effectively what Disney does with their ticketing system, along with at the gate them taking a picture of you so they can confirm "Yes, so and so looks like the photo".
But yeah, all of this is ridiculous on its face as the cheaper and easier solution is ticket plus ID. If you are worried about flow have signs up before check in that say "be sure to have your ID ready before you get to the counter".
The ticketmaster solutions are just bad/half assed.
That is to say, if ticketmater had just done TOPS like the article points out, you'd not need the headache they've created with needing a live internet connection to load your ticket.