Yes? Or at least ish. I mean, I agree they probably do some outsourcing, but I don't think they'd need to do much
They probably don't need much of a sales or marketing team, so that cuts down on people a lot. They have a flat hierarchy, so that means no middle management. They don't really have large customers, just a bunch of individuals, so they don't need customer success managers to manage relationships. HR would probably be run for all Valve employees, so it's not like they have HR employees JUST for the Steam team. Same goes for internal IT and infrastructure, so they probably aren't part of the 100. Probably same with legal. On top of that, IT, infra, and legal teams aren't usually all that big anyway. Like, decent chance that's ~10 people. Not saying it's a direct comparison, but I work at a company of ~200. We've got like, 2 legal people, 3 IT people, and 5 infra people. So yeah, ~10 seems reasonable given their size.
That means the 100 can be focused almost entirely on development and support.
On top of that, there's a good chance they don't actually host a lot of their servers and DBs themselves, so they pay external vendors. I wouldn't really count paying external vendors "outsourcing", but I guess you could kinda make that argument. Same goes for translation/i18n - they're probably external vendors, but I wouldn't call that outsourcing. Same with a number of other services like that.
While there are plenty of things that change over time with Steam, the core platform is pretty stable and unchanging. So they probably have a core group of developers working on new features, and a decent chunk of people on things like vendor and hardware partnerships and support. Beyond that, they probably don't need a whole ton else.
And then yeah, there's probably some outsourcing - I'd imagine that's the case for customer support, maybe one or two other things. I agree they probably have some, but it's not like they'd have hundreds of outsourced jobs. Probably a few dozen.
One employee per every two countries?! Figure it out.
This is a terrible way of thinking about it. Again, I work at a company of ~200. Not saying it's a direct comparison, but it's close enough. You know what we do when we need to support some additional languages/regions? Maybe update some code if there's something unique about the language or region, and then we.... Pay our translation service some extra. That's about it. We don't need to hire more employees for every single country we support, just pay a vendor some more money.
And yeah, if it becomes a popular region, there's some more things you have to do. You probably hire a small team to handle management/business/partnerships in that region, but as I mentioned about, Valve probably doesn't have a ton of need for middle management and business people. So they can get by with even less. Then there's support and IT, so yeah, probably need a few people there and outsourcing for support. But like, that's a few people for a whole region, like the entire EU. You don't need to hire more people for every single country in the EU.
Not trying to say you're entirely off the mark, but you don't scale linearly as you grow. If you are a small startup of 50 people, maybe you have one or two HR people. That doesn't mean you hire one or two more for every 50 employees. You wait until you have 200, then hire one or two more. Then at 500 you hire one or two more, etc etc. Between that, Valve's unique internal structure, the fact that the Steam team is probably supported by Valve's employees, paying vendors for services you don't want to run internally, then yeah, they probably don't need to outsource too much.