Why would they need to subpoena Microsoft and why will Microsoft hand them the data if someone doesn't like my meme? I understand what you are trying to say but it does not make a whole lot of sense even from Microsoft pov. They are not bound by law to hand over personal data to anyone without a warrant issued. If a warrant is issued then it is their lawful duty to give that data, the same would be done by you if you were in their shoes or your office or your family. Law is not optional to follow. But Microsoft doesn't need to do watermarking on memes to track you or to do this as a war against "internet anonymity".