GCM doesn't work in China, so the Android ecosystem there is very different from the world.

Before manufacturers come up with there GCM alternative, each apps actually have there own service to handle push messaging. It is fine when the number of apps is small, but drains a lot of battery when it gets larger. So manufacturers started to introduce some aggressive strategy to kill background processes to save batteries, but it also makes small developers' app less usefull. It is because apps from big corporations usually get a pass, while others will be killed. Now, as far as I know, manufacturers have their own GCM alternative now as an alliance.

So I think even if you don't have it, you eventually need one, because it is too inefficient to let each apps handle this by themselves.