Most of the worlds largest enterprises run tons of this legacy cobol mainframe stuff. They solve really hard problems using this technology and we would be wise not to be dismissive but instead to learn.
With the generation of programmers who wrote the code retiring it’s even more entrenched because even though they rely on that code dearly, few if any people remember why it does what it does how it does it.
For many big COBOL systems that’s long past; in many cases the programmers that were coming on board when that generation retired are near retirement.
Do any of those legacy systems work on "hard problems" similar to how FORTRAN is still used in fluid dynamics, physics, crystallography and chemistry?
One would look at google. https://www.tutorialspoint.com/cobol/index.htm