Engineering tolerances <> Marketing "tolerances" Generally where Intel are concerned the same physical chip is used at multiple marketing price points coz their yields are generally so good. So those of us who OC like the idea of getting something for nothing.
Additionally I guarantee you that OC'ers will
a) Know their TDP rating off the top of thier head.
b) Be running temp monitoring utilities such as speed fan over and above what the bios provides.
All in all an OC'er will have an idea their PC is going tits up long before the average joe.