Well I don't really see why you can't add an apache2 library to any project. The sole limitation is that you must must publish back any change you made to that

Well I don't really see why you can't add an apache2 library to any project. The sole limitation is that you must must publish back any change you made to that specific library under the same license. Apple for instance use Apache 2 for Swift and they clearly aim at closed source project to use it as a library. So what's the matter?