With a healthy corporate culture, being "in" means respecting your co-workers and meeting clearly-laid out expectations.
In a toxic one, it corresponds with social connection, cultural identity, obscuring expectations (and rewards) and zero-sum empire building.
...Or that it worked just well enough while they were creating a platform that set them up as a gatekeeper and quasi-manopoly, and works just well enough to maintain it.
It is useful to be able to talk about those differences. What people have in mind here is that Valve is way more anxiety inducing then average company.
You report to your boss who reports to their boss and so forth. Authority is decided based on your title which is largely determined once at interview time. As is your compensation structure which almost never has bonuses being a significant percentage of the total package.
see also: literally every company in existence.
I realize people tend to become invested in reinforcing the status quo but I am still baffled at how every time Steam comes up 99 out of a hundred comments act as if office politics aren't exactly as powerful and unaccountable as every anecdote about Steam and their cliques.