But a huge amount of them use web technologies which are pretty much OS independent. I'm using Linux for 10 years now and I used to have trouble to work with others because they where all using Windows-only software (proprietary chat client, MS office, etc.) but it's less the case anymore because for many use-cases everybody uses web applications instead of native software.
> It turns out people want fancy, fat UI -- and rendering that server side isn't a very good idea.
That's why JavaScript is the dominant language out there. And with WASM comming, even what's currently out of reach of JavaScript will be doable on a web plateform (except high-end gaming maybe).