<i>The</i> most useful piece of metadata available to anyone harvesting user profiles for surveillance or profit. Governments must love phone numbers. Getting an anonymous phone number for each separate service you register with is practically infeasible.<p>I worry about how influential people like Moxie Marlinspike are seemingly turning the modern &#x27;mobile-first&#x27; development paradigm into a &#x27;mobile-only&#x27; mindset. I don&#x27;t believe in secure and private computing when you are making it very hard for people to use your tools on (or via) anything but the two dominant mobile operating systems.