Many consider it a mistake (I sure as hell do), hence everything else being behind a permissions model. I could ask you why SELinux is necessary in the first p

Many consider it a mistake (I sure as hell do), hence everything else being behind a permissions model. I could ask you why SELinux is necessary in the first place, but the fact is that mistakes are made and learned from, and additional software is made to fill in the gaps. If you want that amount of control, there are plugins that grant it, and using a plugin is much like using SELinux to fill in gaps or mistakes in the platform. Software will never be bug free, and that's not an excuse to never write anymore software.