I don't see how this can be true when no one stays at a single job long enough for this to play out. You would simply be training junior employees to become senior employees for someone else.
So this has been a problem in the tech market for a while now. Nobody wants to hire juniors for tech because even at FAANGs the average career trajectory is what, 2-3 years? There's no incentive for companies to spend the time, money, and productivity hit to train juniors properly. When the current cohort ages out, a serious problem is going to occur, and it won't be pretty.
It seems there's a distinct lack of enthusiasm for hiring people who've exceeded that 2-3 year tenure at any given place, too. Maintaining a codebase through its lifecycle seems often to be seen as a sign of complacency.
