> You can always make web form based applications without style sheets.
Uh, no you can't. Web forms aren't rich enough to build most desktop applications. You can't make vscode, gmail, slack or spotify using web forms. They're just a bad set of primitives for applications. (In the web's defense, it was never designed as an application platform).
Yet - we had some version of all of those applications in the 90s, on every OS at the time. And (mostly) using the platform's built in UI libraries so the look and feel was consistent and delightful.
They're pretty fast to create, relatively consistent, simple and fast/easy to create.
That's not what people want, they want all the flexibility and features of say Gmail or maps. B along with some communication and flexibility. Not to mention running on every OS under the sun, and being able to use accessibility and screen reader tools on all those platforms.