Without any first hand knowledge, I'd assume that the balance of things towards WeChat and away from Play Store/Play Services in China might mean that "Android" really does mean something different in Chinese markets? It's easier to sell an "Android" device if the benchmark is "runs WeChat" rather than "runs the apps I see advertised everywhere" (given the near ubiquity of Play Store emblems on American ads) and "runs the collection of apps I've bought over the last few years from the Play Store".
I don't know where you learned about the misinformation that is "the balance of things towards WeChat and away from Play Store/Play Services in China", which is frankly quite ridiculous because WeChat is just a messenger app with a few added functionalities (social timeline, payment, etc.) — it's not comparable to an app store or a service SDK at all.
Back to my original curiosity, outside of my supposition you think is clearly wrong, do you have an impression that Chinese phones that have forked AOSP and don't have access to the Play Store/Play Services still count as "Android" in China? If so, can you give an indication why that might be different than in America where Play Store/Play Services are nearly synonymous with Android?