> Some areas do, some areas not so much.

It still does change and you have to adapt.

E.g.

> databases (we use a mix of MySQL and PostgreSQL) and he's living off the learning he did 20 years ago when he was a junior Oracle consultant

And there's lots of changes here, e.g. vector stores, all the different query engine improvements, PostgreSQL IO improvements, etc and they all may impact your job. Your optimal query back then might not be the same. Living off the old learnings is like taking a 50% discount on the max potential.

> I live off the learning I did in Linux now that I administer Kubernetes clusters for a living.

And these have had changes consistently too e.g. io-uring and gateway api. You can only be in legacy for so long.