Hey, op / author here. For this design, of course you could use Flex, but the purpose of the article is that a design created with a drag and drop editor by a user, could be rendered responsively. Users could overlap elements and create all kinds of complex creations that we can't slice up in to flex blocks programmatically. The grid provides a way to render just about anything, with a bit of flexibility.
100% not advocating an engineer to ever do this, we only do it because it's automated and there is no engineer present to convert a design in to a website at scale.
100% not advocating an engineer to ever do this, we only do it because it's automated and there is no engineer present to convert a design in to a website at scale.