Earlier quoted context omitted.
the point of them is that you are providing full proper HTML and CSS so client-side stuff kicks in only when it can and needs to be kicked in.
> so client-side stuff kicks in only when it can and needs to be kicked in. All web components are rendered eagerly, so it kicks in immediately the moment it appears on the page.
No, it appears on the page = HTML and CSS is parsed. When you load your scripts is up to you.