That last point strikes me as a very valuable piece of information which I've never seen spelled out before: consultants/freelancers should specialize in a vert

That last point strikes me as a very valuable piece of information which I've never seen spelled out before: consultants/freelancers should specialize in a vertical. (I'm reading between the lines to assume that you don't actually have a problem with teams standardizing around a specific stack, but rather that they shouldn't market themselves that way; either way, that's not really the interesting part.)