Aye. This way, we can control a large number of aspects of the child's environment in which execve() is called, without having to have execve() do all that work for us. We can open files, change the session id, reparent the process to init, alter environment variables, lower process limits, change credentials, change the root directory... the possibilities are legion.

You wouldn't want to have to design a way to pass all of those things to execve(), would you?