This is truly one of the most ill researched articles I have ever read. I thought it started badly and gradually got worse. I read all the way through to find the bit where you mention Directory Services that already achieve what you want Linux to be able to do with AD.
This time LAST year there was 420 million licensed seats of Novell's e-Directory worldwide. This is a product that sits on many platforms including Linux, and many flavours of UNIX, it can perform all the functionality that was mentioned with this article (including password synchronisation) and much more. A developer can bundle a 250,000 e-directory license with his linux application that integrates into e-directory for free, which must make e-directory a very viable product with the Open-Source world of Linux.
I could go on, but I think you get the gist of my opinions. If an enterprise needs a diretory service on Linux then Novell's e-Directory is one of the options and reading others comments below there are others. So may I request that thorough research is conducted before an article such as this is published.