Nobody else has mentioned this, so maybe I'm an odd-ball, but I don't like giving out my phone number to ad-based services, especially social media sites. Wha

Nobody else has mentioned this, so maybe I'm an odd-ball, but I don't like giving out my phone number to ad-based services, especially social media sites. What do they do with that information? It feels like data collection veiled in security. Giving out more personal information is the exact opposite of everything I've learned about privacy and security.