Unfortunately for most nowadays a conservative and a dogmatic neo-con are the same thing. Only two parties, remember?
The 'con' in neo-con stands for 'conservative' (unless I'm horribly misinformed). I'd say that it's less of a matter of 'there can be only two parties,' then it is of them being associated with each other by trying to use such a generic term to describe themselves.
Very odd to describe this as a "conservative" idea. Most conservatives I know object to this sort of sociological determinism, instead embracing the idea of individual responsibility. If anything, they believe in the power of (slowly) malleable culture and institutions to shape outcomes, rather than accepting bad outcomes as inevitable.