Browsers also meet the everything app definition. The only gap I see is that there's not a single identity provider in front of Twitter, Venmo, and Robinhood, which seems to be Musk's vision. When you think of it that way it becomes clear it's about building a single social graph and the lock-in and surveillance risks become really glaring.
iOS, MacOS, Windows, Android, Linux, etc. are already the “everything” apps.
Why the do we need an app that can do everything inside of an app that can already do everything?
It’s like wearing a hat on top of your hat.
I think your thesis about WeChat being more about a domestic choke point over the freedom of computing in China is largely correct.