This is why messaging is a threat to Google and Facebook -- it's an entire ecosystem that sidesteps their channel.
An example like WeChat is funny and interesting because payment functionality is something you'd think should be either a dedicated app (like what PayPal, Square, and others are trying to do), or a core function integrated into the OS itself (like what Apple is trying to do, especially with their new fingerprint thing making their phone more secure).
WeChat being able to get into the payment space is interesting precisely because (a) they are not a dedicated payment company, they've only just figured out how to monetize their user base in a unique and innovative way, (b) they're not a phone manufacturer, and (c) they're not a mobile OS company.
I would not have predicted this at all a few years back. So I think a few years back, I would have agreed with you simply because I would have not thought of it, not because I actually didn't care for it.
edit: coin Henry Ford quote here about faster horses
OTOH, US sites and apps have been moving in the opposite direction. Facebook itself acknowledged this by moving to an "unbundled" app development strategy.