"Some"? The fact that you have to manually access the database backend in order to change a password is a joke, among many.
To actually set someone else's password to a specific value does require running a command line script (not the same as going into db). In my view that is a reasonable security-convinence trade off.
In any case, i would assume a large org would use a single-sign-on extension and not mediawiki's native user management, which would make MW's password management moot.
Disclaimer: am mediawiki developer