If you have to ask...

Nah, jk. I had someone else in mind. Actually a couple of someone elses.

There's also a huge difference between character development and literally playing your own story out independently of everyone else. For example, say we're doing some war campaign RP and your character is a general. It's fine if your general never once interacts with anyone else's characters as long as his actions (battle strategies, etc) directly affect other player's characters. But sometimes you get that one person playing a general...in another war, on say another continent or something. Completely irrelevant to anyone else. That destroys any cohesion the story has, especially if that one person attracts one or two other people to their parallel campaign, but then the two groups never meet and their actions never affect one another. It's kind of like, what's the point? More than a few stellar RPs have been destroyed this way.