It does take time, but when you launch a product that's missing basic features (like a shopping cart, something almost every online store in existence has) you tell on yourself to your customers, and let them know they're not a priority.
I don't disagree that Steam's feature rich platform makes it hard to compete with on that level... but for fuck's sake, at least try a little bit. Especially if your first move is to say they're unfairly gaming the market by... providing something people want.
They don't want to dig into the spaghetti code to make it work.
And considering the lukewarm response to the shitty San Andreas port, they probably don't want to risk more bad publicity by farming it out to the lowest bidder... again.
Looks like it was a console exclusive before it released on Steam, if you're talking about Lost Planet: Extreme Condition (which is the only one I can find by that name).
Do you have more information about the release? Or perhaps it's a different game?
One can have a monopoly without directly trying for it. Especially when it comes to services with a lot infrastructure involved. Once you make those investments, it's hard for anyone to compete against them.
A monopoly just means you control a significant amount of the market. I think, technically, they would fall under oligopoly. Where a few businesses have control of the market instead of just a single business. But the point is they have a far larger share of the market than most others. This is mostly because they create a product that people want to use, instead of making a service that unfairly captures the market through things like game exclusivity or hostile takeovers.
Isn't that just saying you can't sell access to a game on steam (through a steam key) for a lower price than what's on Steam? It's not like they can't just offer a lower price... just that they can't offer it for a lower price bundled with Steam access.
So they can offer a lower price, just not as a third party through Steam itself.