From a business standpoint, it's hard to justify paying support to be technical enough to diagnose an issue such as this. Let's be honest, even senior network engineers would have a hard time debugging and diagnosing this. AT&T doesn't want to pay support staff six figure salaries and I assume most senior network engineers don't want to be support agents (customer facing).

AT&T (though applies to lost of companies) probably need a "unicorn" role of a very technical person that is paid as such, but able to interface with customers on specific highly technical issues.