This. setuid/SUID root was - and still is - a terrible idea. It is a (deliberate) hole in the security barrier. It was an idea spawned out of necessity because

This. setuid/SUID root was - and still is - a terrible idea. It is a (deliberate) hole in the security barrier. It was an idea spawned out of necessity because of the limited expressiveness of the standard Unix security model. Once you let a process run with root or other elevated capabilities, that process should be isolated so nothing about the process can be controlled by the unprivileged user. SUID root utilities violates that.