Edward Snowden showed that global surveillance can lead to abusive system, in which there is no privacy, and everything is accessible by governments.
It is not about your personal advertising. It is not about your grocery lists. It is about creation of abusive system.
If social media have special portals for governments (at least I know about Facebook had one for New Zealand), then it opens a gateway for abuse.
- How do you know you were not abused?
- How do you know your data was not used by China to overthrow western civilization?
- How do you know that your data was not sold to Putin?
- How do you know that your data was not used by Left, or Right political party to change election results, like in Cambridge Analytica?
Companies do not have morality. They care about money, and laws (through fines). If a service does not require capture of data, then that data should not be captured.