As a consumer I find Pitchford's comments to be ridiculous, and Wardell's to be whiny. I have used a number of on-line venues to purchase game content--Steam, GOG, D2D. Steam is hands-down the most effective in stability, support, ease of purchase, ergonomics, content patches, everything.
It's too bad that other studios have to go through a competitor's platform to sell games, though one could wonder why they didn't think of it themselves five years ago and do it first. Valve came up with a good idea and has been constantly improving the implementation. Frankly, as someone who buys games, I think that's great.
In fact, the basis of the complaints seems to be purely financial. There has never been a breath of scandal that Valve plays favorites, delays or slows competitor's offerings, dishes out unequal access, or commits any other form of unethical practice. In fact, it's worth noting that every single comment that came out as a response to Pitchford's original diatribe has stated that Valve could, but doesn't. After all, just because Valve also comes from Seattle doesn't mean that they use Microsoft's business practices.
Why does Steam have a 70% market share? Why are so many of us happy using it? Maybe it's because it works.