Lawyer enters the thread.
It's more common than you think. When complex work is done within power structures, it's just not enough to be "right" about something. You also have to be able to sell your solution to people who are wrong and powerful, which is sometimes not possible.
A lawyer from 10 years ago that memorised some good "rules of thumb" about generic matters such as liability or court procedure won't have to throw out everything they know to be relevant today or another decade into the future.
Meanwhile in IT, I regularly see network engineers upgrading links from 500 megabits to 1 gibabit when they should be looking at upgrading to 100 or even 200 gigabits.
Their mental model of what's fast, relevant, or desirable is "off" by two orders of magnitude. Their knowledge was accurate just a decade ago, but is hilariously wrong now.
I can't think of any other mainstream profession where institutional knowledge is deprecated as quickly.