Uh.
No.
That doesn't really happen often even in console space. Console exclusives, when they happen, are usually funded from the get-go by the platform holder, and usually with partial ownership over the game. That's why you see games like Scalebound - or don't see, as the case may be. Platform holder owns the name, so even if the developer wanted to they can't just release the game elsewhere.
And also yes, technically any platform's first-party developer - nowadays - holds a monopoly to the distribution of its own games. The exclusive right to distribution, control of prices, etc, because they own those products. They own the intellectual properties, they own the products made under them.
Like, if Epic Games was to buy the Metro franchise, and make it exclusive to their store - it would be just as bad for us gamers, but there would still be nowhere near the same stink raised up. Because like it or not, they would own the game, and they would have the right - legal and moral - to put the game on their own store exclusively, like all other publishers are trying to do.