Number one goal of any software service today is to make its offering exclusive in some way - exclusive content, exclusive deals, exclusive integrations, exclusive set of participants (network effects), going super-broad super fast because infinite VC money lets you keep operating at a loss indefinitely, etc.
I could be wrong of course, since I don't know how many AliPay and WeChat competitors there are.
When they play it right, you're forced to choose all of them, or at least a significant subset of them, so that their partially overlapping offering add up to the actual thing you need.