:host pseudo-class

I don't understand why :host is a pseudo-class rather than a
pseudo-element. My mental model of a pseudo-class is that it allows
you to match an element based on a boolean internal slot of that
element. :host is not that since e.g. * does not match :host as I
understand it. That seems super weird. Why not just use ::host?

Copying WebApps since this affects everyone caring about Shadow DOM.


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