We tend to forget about it these days, but the Unix permissions model was criticized for decades for being overly simplistic. One user having absolute authority, with limited ways to delegate specific authority to other users, is not a good model for multi-user operating systems. At least not in environments with more than a few users.

A well-configured sudo or SELinux can overcome this, which is one reason we don't bring it up much anymore. We also changed the whole model, where most people have individual PCs, and developers are often in their own little VM environment on a larger server.