It's not only misguided job security. Silos is what you get by default. You need additional effort to prevent silos rather than some nefarious additional effort

It's not only misguided job security. Silos is what you get by default. You need additional effort to prevent silos rather than some nefarious additional effort to lock information up. People who are uncertain that they're still around in a year are much less willing to put this additional effort which pays off in the long term.