Not having to wrap everything in useCallback/useMemo, callback hell, performance issues with large components, state not representing the correct value after using setState, ... are also burdens Svelte does not have. I think this is a tiny burden, just organise your files properly and it's all good

Not sure if intended, but you didn't update the blog page with day 7 - svelte.dev/blog/advent-...

I really like the new createSubscriber API! Although I'm curious, what really is the difference between using this new API and simply having a state field that is set whenever an onchange event of the media query is received?

If you need state, just use a regular component. Snippets are not supposed to replace components, you can use them to hold SVGs or similar, which doesn't need it's own state.