Yup. Competition is good for the market in general, and for consumers in a more indirect way, but balkanization of content space and having to deal with the crappy apps of me-too competitors is a real pain.

(There's probably some economical theory around this that I don't know, but my gut-feel classification is this: competition is good for consumer when competitors are providing the same, or at least directly substitutable, goods and services. Individual video games - and music, movies, books - are not substitutable goods, so the competition is useful only to the extent you can get the same game/movie from any of the competitors. Exclusive publishing deals make competition harmful to the consumer.)

Yes, there is a pretty standard economic proof that much of capitalism is based on. It says that an economy is most "efficient" (you can take a class on that word), when three pre-requisites are met:

1. Perfect information: Everyone knows the value of everything.

2. Commodities: Products created by competitors are equivalent. This works well for oil and bananas, but not so well for much else.

3. Access to Capital: This means new competitors can start competitors and enter markets easily. This isn't so easy when there is regulation, monopolies, or network effects.

In short, there is a set of circumstances when things work really well. However, in the real world, those circumstances rarely arise.

I don't really want a monopoly, though, having more than one store is better in the long run, even if it sucks having to register for multiple services. At least it's not like streaming where your costs go up the more services you register for.

The ideal would be if Steam could let other publishers plug in their platform for a much smaller cut of the profits and handle sales, forums, friends, wikis, with the other publisher handling distribution, marketing, etc. Or at least if it could function as OAuth and I could use my Steam profile on other publishers' services, carry over my friends list, maybe achievements, etc. Of course that still leaves Valve in a monopoly position, but I think it's an ok compromise.

The problem with "competing platforms" is that they're mostly not competing platforms. Recently Metro: Exodus was pulled from Steam store to be sold as an exclusive on the epic store. This is not competition, this is a monopoly on distribution of a title.

When different platforms emerge where most platforms have most titles (or offer DRM free like GoG or Humble Bundle), then we will have actual competition.