Usually the superiority in aftermarket parts is it allows folks to stand on the shoulders of giants... it's easy(er) to improve upon greatness than create it from scratch. That being said, OEM stuff is 99.99% a compromise of greatness VS cost, so there is generally more than enough room for improvement in a lot of places..... if you're willing to pay for it.
Having done a little bit of building shit from scratch, my buddies and I have a few jokes about 'billet' as well.... on more than one occasion I've asked random fellows about the construction material/alloy for a shiny new part, and I get 'Billet' back as an answer more times than not. We've started playing along at this point. "Oh cool, that must be the new T-7 billet, right?" or "Cool man, billet must be so much stronger than regular metal". Fun stuff.
Attack life... it's going to kill you anyway.