I actually do hang out on Twitter. But not everyone does. A while back I wrote about determining which platform is the best one for you. I suggested setting up a profile on each one and then focusing on just one. So what do you do with the platforms you know you won't be as active on or you won't use at all? Why even have a profile if you're not going to be active there?
People are going to look for you on all social media platforms. If someone is a big Twitter enthusiast, that's where they are going to look for you. If you're not there, they may not look for you elsewhere. So you want them to find you there and then from there go to where you are active online.