It used to be mostly plaintext and basic colors with no responsiveness, under construction gifs, basic images, and flashing text. Before that, just text. We're still learning as an industry. Web technology has not (and may never) settled like the hardware in your toolbox.
Those frameworks are geared for productivity, not possibility. Productivity is where the money is.
As for productivity vs. possibility, I certainly don't dispute that productivity is one place where the money is[1]. However, that doesn't mean there isn't also room for innovation, and it certainly doesn't mean there's no money in doing things better than what you can achieve with Bootstrap, Angular, and a couple of junior developers who don't know much else. In an increasingly monotone and commoditised technology field, more interesting and/or effective presentation can certainly be a USP.
[1] I might question how sustainable that productivity proves to be over the longer term with many framework-heavy projects, but that's a separate issue and probably not worth getting distracted here.
I want to use abstractions and tools where they offer an additional benefit, but without being limited to whatever some predetermined choice of tools or abstractions can do.
So, what you really want to do is just build some apps, not learn CSS. See the difference?
However, we were talking about knowing HTML and CSS vs. knowing abstractions built on top of them. In that context I didn't interpret the post I replied to the same way that you did.
Starting with some specific framework or tool set inevitably limits what you can achieve. Surely the recent emphasis on frameworks over fundamentals has been a major contributor to the Web full of bland, practically identical sites that we see today.