Have WhatsApp spent effort to build "that product" to China, and they would fail on it.
And I don't see WhatsApp is super pissed that they lost this 1.3B market anyway.
And in a hindsight, it is probably better for WhatsApp to not build "that app" for China. Imagine spending all those resources, money into a product and simply turn off by China government overnight. It's a big loss for that investment.
TL;DR do not enter China if you haven't yet finished conquered the entire world.