I remember discussing this with Tantek years ago:
There are a few elements who need to be placed inside of another specific element in order to function properly.
If I recall, he was considering writing “HTML: The Good Parts”.
Anyway, I can relate to what Eric is saying here about web components. My take is that web components give developers a power that previous only browser makers had. That’s very liberating, but it should come with a commensurate weight of responsibility. I fear that we will see this power wielded without sufficient responsibility.