you don't merge back from the main tree to the feature branch.
but the point is that I don't believe that the people who created the commits that you are complaining about would have done any better if they were patches. there was nothing in the tool that prevented them from doing things better. there are lots of kernel developers who would have helped them develop things (and comment them) if they had asked, but they weren't willing to reveal things.
getting things in patches would have probably been _far_ worse, as there would probably just be one big patch for each program (that _is_ the common thing to do when companies fork programs and then release their changes)