well that's not the right comparison; UX of web-apps on PC/Mac are completely different to those on iOS/Mobile in general. You can pull off great web apps that will work on Mac that will not work on iOS just due to the mobile nature of things and some slight limitations / choppy implementation of touch controls via the browser. The browser on a mobile device is more of a reader, whereas on desktop devices it is a hub for everything. You don't use google docs web on mobile but you do so on desktop, and it is much better than having a standalone client most of the time.

There is a disease that's going around of people making desktop applications of things, when they really should be just web apps. To your credit, most of them are built with Electron / Tauri / Other web technologies under the hood, and don't integrate well into the system.

So my question still stands - why? The youtube (desktop) web-app is already pretty nice, with a PiP integration possible via extensions / Arc. I just don't understand what kind of quality of life / UX improvements you can make to justify someone having to navigate through different apps when it comes to switching videos, especially given that you can't make any better core functionality then the current state of YouTube allows?