Eh, there's some validity to that, but the worst of both worlds is to have both a CSS file and then a bunch of inline styles, which is what people here are proposing.

Inline styles make a lot of sense if you're using webcomponents pervasively, but there's a high up-front cost to doing that because you'll have to either a) define web components for everything you might want to style, including existing elements like <p>, or b) repeat yourself a lot.