Treat layout pages like components when using named slots

Let's say I have a _layout.svelte like the following:

<slot name="layout-pre"></slot>

<div id="intermediate">Some other intermediate stuff.</div>

<slot></slot>

And now I have a child view (let's call it homepage.svelte which inherits that layout, which puts some stuff into the named slot, and the rest into the default slot:

<h1 slot="layout-pre">This should come before #intermediate.</h1>

<!-- When rendered, the div from above should get inserted here from the layout:
<div id="intermediate">Some other intermediate stuff.</div>
-->

<main>Since this doesn't use a named slot, it'll just get inserted into the unnamed slot above.</main>

Right now this is not allowed, and the following error is thrown: Element with a slot='...' attribute must be a descendant of a component or custom element. Are there technical or usage reasons why we wouldn't want to treat a layout like any other component with respect to slots?

Start by reproducing the slot behavior with the shown _layout.svelte and homepage.svelte examples, then inspect how SvelteKit validates slot attributes for layout pages. Done means named content from the child page can render in the layout-pre slot while default content remains in the unnamed slot, without the reported error.