Well, there is an old English proverb that applies here: you don't look a gift horse in the mouth. Obviously OSS writers could in many cases do better at communications. But communicating clearly is a skill that is unfortunately not all that common and there is an interesting thing about the very best programmers that I know: they all seem to excel at dialogue with the machine but only a small fraction of them is equally skilled at dialogue with humans, present or in writing. This creates an obvious and immediate problem: without infrastructure those people are still going to be able to create useful software, various tools and so on, but those tools are going to be bereft of documentation and explanation. This is the case for a large chunk of all open source projects and if you look a bit more closely at this you'll probably find that the most successful open source projects are successful primarily because their creators either had great communications skills (possibly even better than they had software skills) or that they found someone to contribute that skill early on in the project.

So what you are seeing is entirely the expected outcome!