Tell me you've never worked at a large company without telling me you've never worked at a large company.

This is pretty standard policy and has been true everywhere I've ever worked. In order to maintain any amount of security or stability, you'll need everyone not only in the same OS, but will prescribe the specific updates/patches that need to be applied. Depending on the industry, you may also need to approve things anywhere from the level of individual applications to device drivers.