Looking at the comments I think that most of commenters missed an important point. It's not just that the app is tracking users, but the messages sent by any non-Chinese user help the regime censor the content for Chinese users. In other words, if you use WeChat, and you send a photo of something that happened in Hong Kong along with some text that explains it, then you actually help Chinese authorities to censor thi…
Many Chinese-Americans have no choice when they need to communicate with family and friend living in China. No outside communication tools allowed in China.
Every Chinese site I've ever used requires phone number or ID verification. Most of them only allow Chinese-registered phones, meaning it's absolutely impossible to communicate with Chinese people from the outside world, aside from a very small number of carefully vetted services like WeChat.
But I fear the rest of the world looked at China and thought, "Wow, we should've done that a long time ago!" Accounts I registered about a decade ago now demand I confirm an email and sometimes a phone number. Email accounts I've had half my life lock me out unless I link it to my phone number and prove my identity. Some services ask for a fucking ID card scan, which prompts me to just drop the service. Some things I've used in the past only accept US phone area codes, which having left the US, means those services are now completely inaccessible to me.
China says it's for state security. They're at least kind of honest that their intention is to keep the population in check and watch their every movement. The rest of the world says it's for personal security. Then another day passes and another heap of phone numbers, names, SSNs, and addresses leak and another identity is stolen.