All good points. Perhaps rather than saying the fixes are straightforward, I should have said it's a straightforward concept to understand. If your app takes forever to load because of a huge bundle, you need to figure out how to make the bundle smaller, somehow. (How exactly to do that is where it gets complicated, like you say.)
Tbh its not just that, you can have small bundles which hydrate extremely poorly.
But yes, I think we are in agreement :).
Can you tell I have mental scars from nextjs bundle optimisation?