Is the point not that they have a near monopoly in the modern PC gaming space?
It’s virtually a requirement for developers who release games on PC to release their game on Steam. From what I recall, developers must also follow requirements set out by Valve regarding what they are allowed to price their game on other platforms.
How is it “virtually a requirement”? Nothing is stopping any devs from selling their games elsewhere, but most of them see the advantages that steam brings to the consumers and don’t bother trying to compete. If steam was buying up publishers and forcing exclusivity then that would absolutely be monopolistic behavior, but they are just beating the competition by being better.
They aren’t just beating the competition by being better.
They’re beating the competition because they don’t allow developers to sell games cheaper than on Steam if they want to sell on Steam. And they have the market share to be able to make it financial suicide for a developer/publisher to not put their game on Steam.
“You can sell your game anywhere as long as it’s cheapest here” smells a lot like a monopoly.