And you can't just poach either because in that case we wouldn't have had juniors to begin with.
As long as there other companies scooping up the juniors (which we cannot assume will happen), this could be sustainable.
This is every industry - barring unionized trades with established apprenticeship pathways - over the past few decades. Either someone does the early-career job-hop dance, or they take on student loans to (maybe!) skip some of that. (And, you know, universities would prefer not actually to train anyone, either. If they can - "highly selectively" - find cohorts who don't need much mentorship then that's much better for their bottom lines.) Regardless, the entire cost and risk of training has been pushed onto individual employees.
Yes, this works well for a small minority of highly-motivated people - who are, of course, vastly over-represented on this board, so few here will object to it - but it prevents far, far more people from ever reaching their potential.
If everyone does it, no one monitors it anymore, and quality degrades the only way out is more tokens.
All they really need to do is convince enough people to adopt lower expectations and accept worse software products. At that point, mission accomplished. They've annihilated the source of value originally provided by people who actually know how to do things.
I mean real profit, not "adjusted profit."