Most people do not have the skills or even the inclination to code an exploit, so the initial coding of an attack routine is a bit of a bottleneck admittedly.

Way back when PPCoin came out though didn't someone demonstrate?

You run into all kinds of bullshit claims of purported solutions but so far bullshit is all they are, as far as I know there are no proper scholarly whitepapers, peer-reviewed journal publications nor the like yet on any actually real solution. Just propaganda spam from bag-holders / stakeholders / scammers / partisans and the like.

The "New York City has not been destroyed by any nuclear bombs therefore New York City is actually less vulnerable to atomic bombs than e.g. Hiroshima" is a particularly bullshit type of argument that one sees all too often.

-MarkM-