I believe everyone is familiar with the popular saying that one can have 10 years of experience or 10 x 1 (the same) year of professional experience. If you don't get the difference - it's all about being exposed to new experiences (that can be substantial in spurring your personal development) for 10 years versus being stuck for 10 years with something that could have been fresh and inspiring for 1 year at most (because in all the subsequent years one just re-applies the already acquired knowledge thoughtlessly).

To simplify the following consideration, let's call the 2nd group (10 x 1 year of experience) the "old juniors" - mainly because they appear stuck in the same, narrow spectrum of limited experiences that constraint their personal development. They always felt so good being "right" (not questioned by the rest of the organization), that right now they find it their innate privilege (the mark of their status within the org).

The "old junior" oligarchy

Until now, I've used this concept to illustrate why the job market valuation of certain individuals with similar tenure may differ a lot. But that's not the whole story. Please keep in mind that the global job market is very different from local work environments (stating it plainly - particular companies). While in general the "old juniors" are typically a pitiful group of people who can't understand why no-one (except their former employer) wants to fulfill their financial expectations, there may be companies where the "old juniors" form the whole "top tier" of engineers on the company (and co-define the technical vision for the whole enterprise).

Old Junior = Low Overall XP + High Local XP

Even if some Young Buck appears on the horizon, it's easy to set her/him back in place, by shifting the balance of importance towards Local XP (being familiar with semi-obfuscated legacy stuff).

That's a very dangerous scenario I haven't covered at all until now. It usually happens when the best engineers in the company are never challenged, never face the external verification, are not measured vs market-wide measures, standards & benchmarks. They do fine locally, because the organization doesn't know any better. There are no external stimuli that could either re-align their views or inspire innovation. Let me give you an example: they've never seen how to implement observability properly (because they've always worked in an organization totally ignorant of observability's existence), so it has never been on their agenda.

Getting out of the local optimum

In many organizations, the longer the "old juniors" remain at the spearhead of the engineering organization, the worse are the outcomes. Their position becomes virtually inviolable, their opinions are treated (unquestioningly) as facts, they are simply untouchable. And - in the end - the organization's point of view remains limited as well. The current state is satisfying enough, because no-one knows (has experienced personally) that things could have been significantly improved (due to a little bit of "out-of-the-box" thinking).

That's why EVERY engineering organization should keep looking for an external talent (to refresh/reset org's perspectives), not only in terms of fresh & adaptable juniors (ambitious, hungry, open-minded, eager for experimentation), but also experience hires who could provide completely new standpoints & cause some disturbance in so far calm waters. These people should be given enough space and autonomy to enrich the work environment before they get "tamed" and overwhelmed with the luggage of local inertia.