I think you're confusing your cherry-picked comparison with reality.
LLMs are eliminating the need to have a vast array of positions on payrolls. From copywriters to customer support, and even creative activities such as illustration and even authoring books, today's LLMs are already more than good enough to justify replacing people with the output of any commercial chatbot service.
Software engineering is being affected as well, and it requires far greater know-how, experience, and expertise to meet the hiring bar.
> And when you talk about applying this same tech, so confidently, to domains far more nuanced and complex than (...)
Yes, your tech job is also going to be decimated. It's not a matter of having PMs write code. It's an issue of your junior SDE armed with a LLM being quite able to clear your bug backlog in a few days while improving test coverage metrics and refactoring code back from legacy status.
If a junior SDE can suddenly handle the workload that previously you required a couple of medior and senior developers, why would a company keep around 4 or 5 seasoned engineers when an inexperienced one is already able to handle the workload?
That's where the jobs will vanish. Even if demand remains there, it dropped considerably as to not justify retaining so many people in a company's payroll.
And what are you going to do, them? Drive a Uber?