While fryke is quite correct, and being 'root' does allow one total access to all files and folders (directories), however - Mac'ers have had such access from System 1.0 to System 9.2.2) [some say the last 'System' was 7.6.1, after Apple changed the Operating System's name to 'Mac OS ...' when Copland containing '8' appeared)].
Quite a number of (non-MacOS X) Mac'ers (greater than 20 million, in fact) actually used their Macs as such (as 'root', unknowingly of the term) with no 'root' related problems or dangerous results. Yes, there were several who did. Then again, there are millions having problems with MacOS X, and they are not logged in as 'root'.