I don't disagree either to be honest, but the reality is we live in a world where almost every business is dependent on a presence that shows up in web browsers

I don't disagree either to be honest, but the reality is we live in a world where almost every business is dependent on a presence that shows up in web browsers. This puts enormous pressure and real dollars spent on making web browsers and the HTML & CSS ecosystem super fast, accessible, etc. Thousands of developers are trained every day how to make basic HTML & CSS experiences. Any UI system that throws all that away and tries to build up a similar ecosystem from scratch is going to be churning and churning for years. Don't forget browsers are pretty spectacular runtimes. V8 and its JIT compiler is arguably one of the best runtimes of any language in the world. Sure the very first view of a page is going to do some parsing, etc. but as it runs it gets faster and faster with core functions and components compiled on the fly into platform machine code. The sandbox and security and encryption support in browsers is top notch and supremely battle-tested and hardened. With WASM now pretty mainstream we're starting to see entirely new frontend UIs coded in languages like C++, Go, Rust, etc. that are incredibly fast too. If you squint hard enough the browser is really no different than the JVM or .NET CLR these days--it just has 20 more years or so and an order of magnitude more developers working on improving it.