reading nothing but those you already agree with is dogma at it’s purest.

But again you presuppose that you agree with all these people which is really not the case.

And the example you gave was of the Austrian economists, which is an unfair example as they are a fairly fringe group relative to the rest of economic thought.

It's not so true any more. Neoclassical economics are very close to the Austrian school these days.

What I’m trying to get to is, good luck studying all that while reading only leftists.

I didn't say that. I said that it's not a good point to say that it would mean you don't read criticsm as if there isn't tons of criticism within the left. Also that most CRITICISM of the left (not most things that are said in general) outside the left is really not constructive at all.