It might not actually be banned; there are reports on Twitter and Reddit saying it's just a DNS cache poisoning attack similar to one a few years ago. No one's posting good verifiable info though so I don't really know. Steam definitely seems to be inaccessible in China right now, but why and whether it's intentional is not yet clear.
But a ban can be expected, as Chinese government enforces a system that allows only pre-approved games to be available to the country citizens. Chinese gaming companies too had been hit with bans.
This correlates with some of the other reports I’ve read and I appreciate your skepticism. A “ban” is certainly not outside the realm of possibilities in China, especially given some of the new social policies, but we cannot afford to react like this whenever the word “China” makes its way into a headline if we want to draw attention to the real “bad” things.
