That is: you're presupposing that a JavaScript framework is actually necessary in the first place. I'd argue that the whole concept of a JS framework is the epitome of chasing after shiny and complicated things. If instead you start with just plain ol' HTML and incrementally add CSS and JS as actually needed, you're much more likely to end up with a much simpler and more maintainable end result (or, at the very least, you will have figured out the actual and specific reasons why you might need the additional complexity of, say, Sass or this week's JS framework).
That is: you're presupposing that a JavaScript framework is actually necessary in the first place. I'd argue that the whole concept of a JS framework is the epitome of chasing after shiny and complicated things. If instead you start with just plain ol' HTML and incrementally add CSS and JS as actually needed, you're much more likely to end up with a much simpler and more maintainable end result (or, at the very least, you will have figured out the actual and specific reasons why you might need the additional complexity of, say, Sass or this week's JS framework).