How is it hand waving? It's literally true a large corporation can fire a customer support agent while sponsoring a software engineer, it is not interchangeable talent
I doubt that's the argument they're making. They're saying they are laying of a software engineer in one org, and hiring another software engineer in a different org. Not cross functional roles.
The army of developers stuck working helpdesk right now because they can't find work, would like a word.
Maybe they weren't exactly doing that. Calling a developer something else doesn't make it so.
Talent can be trained, less across jobs (although it's often what public services ask to entrepreneurs in some European countries), much more across departments.
If we had a union we would be training people from customer support to engineer.
I truly believe that software would be improved immensely if all developers spent a few years doing tech support for the elderly.