The title says it all, and I'm sure most private servers has implemented this function in order to combat the "ID is already logged in" issue, especially for those characters that wont disconnect after passing the inactivity period and having to wait for next server check/reset to get disconnected. Don't see any reason or potential to abuse this feature too, unless your account detail is compromised and all that.
I don't believe that we really have an issue regarding accounts getting stuck logged in until the next server check. I've tried searching for recent threads regarding the issue but can't find anything. I know we did used to have some issues regarding this, in particular with the Cash Shop, however they seem to have been solved now. Additionally, most cases of the "unstuck character" function are prone to character rollback issues, due to how it forcibly marks your account as offline whilst character data may not have properly been saved to the database yet. And if there is a method found which can cause your character to get stuck logged in, the use of such function can then lead to possible dupe exploitation.
