The data-masters at SteamDB believe that China actually is being recorded for Dota 2 and CS:GO, and if their research is accurate there just aren’t as many Chinese as we expected.
This was a point of contention because those games have separate launchers outside the Steam client in China, through Perfect World, and because there haven’t been significant increases in player numbers alongside China-specific events. The “standalone” launchers for Valve’s games are stripped down versions of Steam, but they are still versions of Steam. You can even access Chinese regions of those games through the normal client simply by setting a launch option. And we do know - thanks to PUBG - plenty of Chinese players are using the standard client.
That means there’s little reason to suspect Chinese Dota and CS:GO players aren’t being counted on Steam. Correlating Dota 2’s public matchmaking records against the Steam hardware survey’s language reports suggests roughly equivalent player percentages in China, and CS:GO’s dedicated servers offer a glimpse of how matchmaking breaks down worldwide.
These are all decidedly non-scientific findings, but the evidence is compelling, suggesting that Steam actually does account for all these players. It’s just that China’s just not that into Valve’s biggest games. That could be because those two titles are directly competing against two of China’s (and consequently the world’s) most popular games in League of Legends and the shooter Crossfire.