> All browsers that matter now support a solid common set of features which should be sufficient for the vast majority of cases.

All it takes is one of those non majority use cases and you're going to need some kind of dependency to get things consistent

Frameworks like Vue 3 don't actually work on older browsers since it requires ES2016 support in the browsers.. that means IE 11 and older browsers are out. With Svelte you need Microsoft Edge (IE 11 is not supported). Also, it requires Firefox 74 (released in 2020) or newer Firefox versions.

With React, you can make it work with older browsers using Polyfill etc.