It's a way to capture data to use inference models to understand who you actually are, your tastes and personality.
Yes, Instagram/FB/Meta do the same, Google does the same, the difference is that Meta and Google are not the government or, worse, an adversarial government from your nation that could weaponise such data. Tailor-made suggestions and recommendations already work pretty well for adtech, tailored suggestions of content with aims to slowly shift cultures and perceptions is much more dangerous than serving compulsive consumption.
And yes, very likely the US government has some access to FB/Instagram/Meta/Google profiling data, I also believe that's dangerous (even more that I'm not an American citizen, nor live in the USA and still am probably surveilled by its government) but in a different degree and level than what TitTok and China might be able to.