There is a huge pool of exceptional junior engineers

Not mentioned in the article : interns/juniors are too expensive these days ; seniors offer better value per dollar of comp.

Why not just pay them significantly less than seniors? if there is a surplus of juniors shouldn't the invisible hand of the market adjust the salaries accordingly?

The invisible hand of the market is saying to hire offshore

Depends on what you think the cause is. They can’t work for $20 a month legally in most cases.

The invisible hand of the market is playing games with promises of AI allowing one senior to do the work of a senior and 4 juniors.

Whether or not it works will be something we find out long past the early-experience tenure of those junior engineers.

Anectodally, I've seen that some newly graduated engineers prefer to forgo the job search altogether, rather than lower their comp demands to get a foot in the door.