Ticket counterfeiting is the core problem that they are trying to prevent. If there's a fallback method then that fallback method can be abused to forge tickets.
EDIT: I know complaining about downvotes is a downvotable offense itself, but I'm genuinely curious as to what is objectionable about this comment.
Forgery isn't relevant.
He's a known individual, a season ticket holder. He's not some random dude showing up with a paper ticket.
China's solution: your passport is your ticket. Not great for privacy, but persumably you also want to check that people banned from a stadium for their behaviour don't get in anyway.
It's very elegant.
The first time we traveled domestically in China I kept thinking that my wife had to be mistaken, there has to be some kind of confirmation we need to show in order to board. But nope, it literally is just show up with your ID.