Much of RP, all RP not just MMO RP, tends to be long term. In tabletop you have a campaign that usually lasts for several sessions to form a campaign. Forum RP generally lasts a long time due to the time between posts. And this attitude carries over into MMOs, to some extent. Not all RP is long-term, but I think people generally gravitate toward the longer term.
Let’s take a closer look at this and see how it fits into MMO RP where things tend to be a bit more ephemeral sometimes.