I work on them full time (not doing application programming and so I can't really speak to COBOL) but this is mostly accurate as it relates to the environment.

A lot of these services are completely transparent to the application, but that doesn't mean they are totally transparent to the entire programming staff. The system configuration and programming is probably more complicated (and lower level usually, certainly YAML hasn't really caught on in the Mainframe world outside of the Unix environment) all things considered than something like k8s.

So that's where a lot of the complications come in to play. Every application migration is going to necessarily involve recreating in Kubernetes or some other distributed system a lot of those same automations and customizations that decades worth of mainframe systems programmers have built up (many of whom will no longer be around). And however bad the COBOL labor shortage really is, the shortage of mainframe assembly programmers and personel familiar with the ins and ours of the hardware and system configuration is 10x worse.

It should also be noted that not everywhere that has a mainframe has this issue. There is a wide disparity between the most unwieldy shops and the shops that have done occasional migrations to new LPARs and cleaned up tech debt and adopted new defaults as the operating system environments became more standardized over time. In the second case where a shop has been following the more modern best practices and defaults and has fewer custom systems lying around, ... the amount of effort for a migration (but also in a lot of ways, the motivation to take on a migration project) is lessened.

The case where some company is just absolutely desperate to "get off the mainframe" tend to be cases where the tech debt has become unmanageable, the catch 22 being that these are also the cases where migrations are going to be the most likely to fail due to all of the reasons mentioned above.