Why do "Hardcore" titles need to be rated "M"?

[--OkeyDokey--]

nordlead said:

--OkeyDokey-- said:
Nobody ever said that. Stop making stuff up.

no one says it explicitly, but typically you get lists like

GTA, Halo, Gears, God of War, DMC, Killzone, and the like whenever someone states what a "hardcore" game is.

 

That's because, coincidentally, 90% of popular games among Microsoft/Sony fans are M rated :P