I think your misunderstanding the goals of alibaba / Tencent. The derive their value precisely from their strategy of doing lots of things ok instead of one thing well. They are "platforms" not applications. And if they stuck to what they each did well in the beginning they likely wouldn't have been anywhere near as successful as they are now.

Also I think it's too early to tell whether how their worldwide expansion plans will play out. It's worth noting that between them they own a slice of most major tech companies in SEA. I wouldn't be surprised if thats not the only part of the world either..