Are Web Components a thing?

No, except for public libraries (e.g. a datepicker that works in native, angular, react, etc)

1. You CANNOT pass stylesheets to a web component from the parent. CSS isolation might seem cool, but when you realize you have to load your stylesheets into, say, a shared login page, it's suddenly a lot less appealing.

2. You have to import a bunch of scripts, and then conditionally load them with custom-logic (as of now) if the element actually appears on the page. Or you load a bunch of crap.

3. Polyfills, polyfills everywhere - yes, I read the article and I know it said they are working on support for Edge.

4. Managing your source code and deciding where to host the components is icky.