CSS is designed for typography and layout. It was never designed to render arbitrary geometric shapes - something like SVG should be used for that. This is just clever hacks pushing the box model to its limit.
I don't think that "it was never designed to" and what you should do with a technology necessarily go together. A lot of innovation comes from doing things with technology that it was not originally designed to do. You should be aware that you are beyond the intended purpose, but you should not let that stop you.
Yes, a thousand times yes. I assure you that in the 1970s engineers were telling each other that using 8-bit microprocessors to build “toy” computers was outside of their intended purpose.
