I understand that the typical Photoshop workflow became burdensome, but to fly wildly off the other end of the spectrum and design directly in the browser never made any sense to me.

A critical step in any design process is experimentation, which typically involves bouncing between sketches, high fidelity mockups, content strategy, structure and user flows, and evaluating technical opportunities/constraints.

That said, I think the underlying ideal is about embracing the web for the medium that it is — and not a digital incarnation of print/graphic design. Which is fair.