I don't want to too into the weeds of Steam here, so I'll keep this one really brief:
>but the fee for the promotion
I don't think 'putting product on shelf' is 'promotion'. IF that's your only reason and begging the question leads to "becasuse we have 90% of the userbaase", that's a monopoly. Steam is lauded by their audience for only using their local history to recommend games (i.e. they have a realtively simple tagging system they rely on to serve games), so I wouldn't say this is anymore promotion that Google Search is promting "best game 2024" when I search "best game 2024" (in some utopia where the first 3 results were SEO slop).
>If people are willingly paying this because the promotion is worth it, that's not necessarily a monopoly.
I really hope people day understand the difference between "monopoly" and "monopolization", because this seems to always come up in this topic.
"Monopoly" is a very mechanical, neutral term, legally speaking.
>The term “monopoly” is often used to describe instances where there is a single seller of a good in a market...However, despite the general animosity towards monopolies, not all monopolies are illegal. Examples of permissible monopolies include... Monopolies created purely by one seller having a superior product, business acumen, or having good fortune (ex. online search engines, social media sites)
So yes, you can in fact say Steam is a monopoly (in an objective, legal sense), but also argue it not being illegal because "seller has a superiod prouct/business". Monopoly is not a scary word by itself.
In terms of its 90% marketshare and indusry warping effects, it'd be very hard to argue that Steam isn't a monopoly. It'd be easier to argue Google/Apple in mobile aren't monopolies; At least they have each other to shield from their duopoly. Steam has no contender in the US.
"Monopolization" is a scary word.
>In United States antitrust law, monopolization is illegal monopoly behavior. The main categories of prohibited behavior include exclusive dealing, price discrimination, refusing to supply an essential facility, product tying and predatory pricing.
One leads to the other, so I don't blame people for conflating one or another, but it's an important distinction if we're going to start trying to talk about what is/isn't a monopoly, or monopolizing behavior.
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So, does steam engage in monopolization? Yes, but in much more subtle ways than what Apple/Google are doing. They are very smart about it because they care a lot about consumer feedback, and consumer feedback drives a lot of discussion on social media. But that's a discussion for another inevitable day.