Well, sort of. It does still have many costs baked in, such as inflation and issues relating to PoS. I think that more than PoW vs PoS it's the other parameters that are more important and which give good transaction speed etc.

PoW has a hidden benefit in the way that it works though as compared to PoS, although not as much compared to this "Proof of Brain" as they call it that Steem has.

PoW (as does "PoB" in a sense) creates a lot of noise (figure of speech) which acts as a vortex around the blockchain, sucking in spectators and capital. That capital helps build the industry and incentivize new development. PoS has a harder time doing this, at least initially and especially did so pre the ico-craze. (Hence why most people initially rejected it as a ponzi scheme)

You can think of it a little bit like gambling. Half the fun of a one armed bandit is actually pulling the level/hitting the buttons manually, hearing the sounds it makes and waiting for the result. That's why people feel in control and want to play it over and over. If they had much less control and feedback, they would not be as engaged and not bet as much or as many times. It would be comparatively boring and less taxing for the brain to predict the end result.

So yes, PoS doesn't put in as much work, but with Bitcoin PoW is like a game - where miners "mined the gold coins" and got rewards in a lottery - and is also accessible without engaging in DPoS politics.