> Some developers [...] think that that one system only they know is job security
"You can't be promoted if you can't be replaced."
"You can't be promoted if you can't be replaced."
I hate all sorts of gatekeeping behavior but I especially despise having to wheedle information or effort out of someone like that. They almost invariably have an ego that is out of proportion to their contributions.
Side note: Occasionally I have seen people who take on the thankless task of being a maintainer of something no one else wants- those people tend to welcome others and share as much as others are willing to listen to, so being the single person who knows something doesn’t make you a gatekeeper.
It’s the gatekeepers that I hate.
I like your framing better!