Isn't the problem of including only the code the component actually needs already solved with dead code elimination? So the framework authors can include new features but as long as your component doesn't use them the code for those feature does not end up in the final bundle you serve to the user.
I sure am missing something here because the author of Svelte is actually also the author of rollup.js [1] which does exactly that, it eliminates dead code via its tree-shaking mechanism.
As far as I understand, ReactJS is a tightly weaved 40kB chunk of code which will be delivered to the browser no matter how ferociously you shake the tree.
Unfortunately, UI frameworks are extremely hard to modularize in a way that makes them amenable to tree-shaking. So you're left with the alternative – cobbling together your own pseudo-framework out of 'small modules', which loses all the ergonomic advantages of a good framework. As you might imagine, I've been thinking about this problem for a long time :)
I sure am missing something here because the author of Svelte is actually also the author of rollup.js [1] which does exactly that, it eliminates dead code via its tree-shaking mechanism.
[1]: http://rollupjs.org