It is, still. You want separation between your paragraphs and other elements; you don't want the first and last children of a box to be separated from the edges of that box. Margin-collapsing does that (sibling boxes collapse margins together, first/last collapse with parent and shift their margins "out"), but it's difficult to do otherwise.

That said, you could do one-sided margins better if we hadn't had naked text in the layout model. If everything was wrapped in elements, then text at the start of a container element wouldn't require a margin-top on the first child element, while text at the bottom wouldn't require margin-bottom on the last child element. Naked text is a mistake. (And I just added it to the list. ^_^)