This is an interesting perspective(and a great roadmap for juniors to try to improve), but I think for the most part the thesis is wrong, at least in my experience.

Companies do not hire juniors as some long tern play to develop them into good engineers. They hire juniors because they have junior level tasks that need completed.

That does happen, and that junior level work is constructive, but what I've also experienced and noticed is that companies put a lot of effort into finding and hiring exceptionally skilled juniors (industrial placement schemes, graduate fast-tracks, etc.) where they can make safe bets on those people delivering significant value to their companies/projects. Some bigger companies do make an effort to build a mutually beneficial working relationship with a clear 5 year career roadmap (some sectors really struggle with those best candidates choosing FinTech instead). I've worked with high-performing junior programmers that have (quantitatively and qualitatively) dramatically outperformed experienced mid-level programmers, so I'm always an advocate for investing in them.

> They hire juniors because they have junior level tasks that need completed.

I have never worked at a place where this was true. Either senior devs would pound through the tasks, or we’d cut them as unimportant.

The only reason we ever hired a junior was because we saw potential and thought they could grow into solid colleagues.

Not anymore. We give those tasks to genies and hire juniors as apprentices

>Companies do not hire juniors as some long tern play to develop them into good engineers

Working for companies, as a manager, I have. I have said to my management that is what my intention was, and subsequently hired people for exactly that.

We used to hire explicitly to train junior engineers in the days before the dotcom boom.

Stock options which vested over 5 years were meant to make it worth everyone's time.