I'm pretty sure the vast majority of the people who are anonymous are robots and stealth marketers. Normal people aren't usually willing to put in the effort to maintain their privacy. They use their "anonymous" social media and AI accounts on devices tied to their verified credentials (Google, Amazon, Walmart, Microsoft, etc.)

My theory is that these companies want identity verification to prevent swarms of bot farms from clogging up their servers. Up until this point, the drawbacks of identity verification outweighed the positives.