Your wrong.
Hacking a system with DoS attacks is 'modern' hacking as you speak. I am not referring to this kind of hacking. I am instead talking of a hacking that requires brains to solve problems. Your right about it being a unix tutorial though. It is, and a good one at that.
Also, the levels 0 through about 10 or 11, are not your everyday hacks, but they would not start you out at buffer over flows...
Take some time to learn unix, and just have fun. That is what it is there for.
Kryptik