[ragerino]

Problem here is CSS, JavaScript, and HTML. You might use variables, functions or attributes, styles, tags, that would interfere with other components.

That's why you want an additional layer like Angular2+ taking care of that.

[clairity]

yes, that's the scoping issue i mentioned, which can be solved other ways, like with admittedly-not-ideal randomized classes (or 'for' attributes, perhaps with css-style selectors rather than just for id's).