Sure, sure, those areas are fine places to discuss capitalism.Nope.
You can discuss capitalism 'till your heart's content in the Libertarian, Liberal, and Conservative political areas. All three rely heavily on it to differing degrees; just pick the political philosophy that fits you best and have at it.
But the first 2 include many socialists, so by your reasoning,
should their forum not exist?
I don't know if a capitalist DIR would have much traffic, but
is there any good reason to oppose it?