People don't trust companies who want an email address. You get extra spam, the company or their successors and partners sell the email address, poorly secured computers and cloud nonsense almost ensure it'll be stolen, and nowadays if you have an incorrect opinion you could easily be doxxed, even by people inside of these big tech companies and startups.

You may not care about these issues, and you might have the correct opinions for now which don't irritate the tech overlords. But lots of people have learned the hard way that providing an email address is, at the very best, going to result in spam. At the worst? You could be physically assaulted, lose your job to an outrage mob...