Early last year, I left a site I’d been a member of for almost 6 years – Digg. Why? Well, because they changed their user system. Instead of having a Digg account, you had to use your Facebook account to log in. They’ve since changed this to allow you to use your Twitter or Google Plus accounts as well. The problem? Quite simply, I don’t have a Facebook or Google Plus account, and have absolutely no plans to get one. I do have a Twitter account, so I could return, but that first announcement was the “last straw.” But it points out something that’s becoming an increasing problem: The assumption that everyone has a Facebook account.