Given the other restrictions on internet use in China, it should have come as no surprise, but I had no idea this was the law of the land there.
https://scholar.google.com/citations?view_op=view_citation&h...
"China takes a different approach to protect the ad-based business model under unfair competition law and bans ad blocking software directly by regulation. The Chinese courts held that providing ad blocking software is anti-competitive under a vague general principle of the Anti-Unfair Competition Law."