Web development doesn't bind you to a specific platform. And modern desktop apps are overwhelmingly Electron (i.e. based on a web stack). It is just simpler to develop than native, and gives you portability out of the box.
And if you're a mobile developer, you must have a Mac, because the proper tooling for iOS does not exist on other platforms. So even if you target multiple mobile platforms, you'd develop it on a Mac.
I think there is sort of a Pareto distribution, like 20% of apps generate 80% of the money or something like that.
Quick googling confirmed it: "Spending on iPhone users accounted for 68.13% of all consumer spending on mobile apps, while Android remained with a 31.87% share of app spending worldwide in 2024".
So while it is 30% in users count, it is 70% in spending. If you want your app to generate money, you'd have to make an iOS version, otherwise it would be irrational.
Same logic applies to desktop apps. It is irrational to spend resources on a native version if you can get to market faster and cheaper with a web-based thing. So from the first principles, today's successful and popular apps must be coded like that. Surely, there is still a lot of legacy...
Nice logic, except forgeting that there are countries where iOS hardly has a presence, and companies on those countries want to sell their stuff to people on that country, not foreigners on other countries.
And if you're a mobile developer, you must have a Mac, because the proper tooling for iOS does not exist on other platforms. So even if you target multiple mobile platforms, you'd develop it on a Mac.