But I don't (necessarily) follow friends on Twitter.
The reason is quite simple: that's not the point of Twitter for me. One of the most common questions I ask myself when interpreting a platform and its role in our daily lives is, "how can this add something new and how does it relate to existing channels?".
My friends and those I've personally met are on Facebook. It's their place in my digital life. Period.
As far as I'm concerned, Twitter is not for me to engage with friends. It's for me to find about people who are willing to share what they know, what they read and what they're passionate about. It's also where I read my news and favorite blogs, which contributes to that same logic.
Sure, I may find friends who happen to fit into this category of people who I find worth following. But it's not just because they are my friends. It's because they act according to what I expect from Twitter, and they happen to be my friends too.
There's a point to this. Know what to expect from each new platform you're in. And know what to expect from each person you interact with.
Different platforms should mean you have a specific purpose in each one of them, and all these purposes when put together represent who you are, hence your digital "self". Otherwise, why use different platforms in the first place?
"Because it's hip" is not the right answer.