I think the long keys are a big put off for many. There must be a lot of dead accounts on here where the owners didn't save their keys properly first time around and started another. I know three currently active people who did that. 😆
I guess we also aren't really that similar to Facebook, despite the many comparisons I used to see when I first started here. It's improved on the usability side a heck of a lot, but still not as user friendly as the social media platforms people are used to.