Living in China for the past two years -
Important thing to remember - in China and in most of South-East Asia the tech boom came at a later stage when smartphones were already prominent. Android + Chinese manufacturing made it possible to produce cheap smart phones. The result is that these countries have completely skipped the laptop phase and went straight to smartphones, most of the population doesn't even know what a laptop is.
What the west calls eCommerce (amazon, Ebay etc) is called mCommerce in Asia (Taobao app, JD.com App etc). Asian consumers find it easier and more natural to shop using smartphones rather than laptops like Western consumers.
Oh and yes, When I leave the house I don't even take my wallet, everything is paid using wechat.
I've been in China as a tourist for three weeks two years ago. I paid everything with cash. Easy.
What would I do now if I have to pay with WeChat and I obviously don't have a Chinese bank account? Tourists don't have time to waste in banks and unless bank accounts are created and activated on the fly it would be pointless to open one. Maybe open an account in advance from home? Is that possible? Or WeChat and Alipay start operating with accounts in multiple countries.
You don't actually need to have a bank account in order to use Wechat payment. Someone can just send you money over wechat and it would still work, just a 1000rmb/month limitation. If you're a tourist it should be fine.
Oh and yes, When I leave the house I don't even take my wallet, everything is paid using wechat.