Standard Oil was not an absolute monopoly. Nobody was forced to buy from them. And yet.
An egregious standard is still egregious. The excuse has always been, well, Nintendo made the console, sold on thin margins, and they manufacture the carts, sooo an entire third must be reasonable. But Steam proves the only reason is that they can get away with it. They don't need any force besides their existing dominance, to maintain that dominance.
It's not a problem. But it easily could be. That's all anyone's talking about when they worry about the company after Gabe.