I know plenty of people who were hired as mid-level C# developers, kept being a mid-level C# programmer, and will be happy to be mid-level C# programmers (with salary increases of course) for the next 20 years.
If you work in an risk-averse industry like banking or aviation, you're not likely to experiment or learn anything new on the job.
true; but in the devops world, you absolutely have to keep learning new things constantly. There's always new tools. It's even a hazard that you get too distracted learning new things to be effective at the old stuff, and I've seen that drive horrible decisions to adopt new technologies with no driving business need, just because the engineers want that on their resume. There does need to be a happy medium.
In context, it means that the people being put in charge, the "majors and lt colonels," have never done the job, so they're unqualified, no matter how smart and dedicated.