Yes, partial source is still very useful. I don't think the law should allow for it though as companies could intentionally put as much as possible into "propri

Yes, partial source is still very useful. I don't think the law should allow for it though as companies could intentionally put as much as possible into "proprietary" libraries that they conveniently only license for binary distribution from a totally unrelated company that for no reason at all is owned by the same stakeholders. Much better to just require everything to be there and then have the industry adapt.