I think the shadow DOM has come a long way and is now used for creating functional components behind the scenes before the page renders. Here is a new overview by google of the v1 version of the shadow DOM that has come out:
So this year I decided it was really about time I applied for the
@vExpert subprograms, and guess what! I'm in! So Thanks to our Programme Manager @vCommunityGuy and Sub Programme Business Units!