re: HTML: layout and positioning is the domain of CSS, not HTML. HTML's purpose is to provide semantic structure to the content and non-semantic styling hooks (divs and classes) for CSS.

It's true that layout has sucked for a long time (more accurately, it hasn't really existed in CSS), but with the coming grid spec, it will finally get a lot better. Flexbox is great for solving certain problems, but wasn't intended to deal with overall page layout. (Basically, flexbox is for laying out one dimension -- a single row or column -- whereas the grid layout spec will handle two-dimensions.)