That's overly reductionist. The OS is an abstraction layer between the hardware and applications, such that you don't need to write everything bare metal (like

That's overly reductionist. The OS is an abstraction layer between the hardware and applications, such that you don't need to write everything bare metal (like it happened in the 70's). In the past (read: 80's and 90's), that mean you'd have applications running on top of your OS, so you could delegate screen, device drivers, I/O, interrupt requests, and everything else to the OS. Now we're in a different abstraction layer. The browser became your interface to the hardware in many respects. If you're an application developer, you can develop "for the web", instead of targeting each OS individually. And with WebUSB/ WebGPU/ etc, the browser becomes even closer to a real OS. Now, it's interesting that mobile apps push us back to the 90's model. The promise of "write once/run everywhere" is gone, and you'll not only develop at least 2 separate mobile apps (potentially more -- e.g., tablets, TV, gaming consoles), but also deal with different OS APIs and different AppStore policies.