I would guess what they want is the ability to link behavior outside of WeChat (e.g. looking at computer monitors on Amazon, and then reading tech news on the V

I would guess what they want is the ability to link behavior outside of WeChat (e.g. looking at computer monitors on Amazon, and then reading tech news on the Verge) with your profile on WeChat. Apple’s changes are in part designed to limit the abilities for entities to track you via third party cookies as you go around the web; device fingerprinting would be a substitute for those third party cookies.