Though i will agree with everyone saying this wont fix the "problem". If they made it significantly worse to leave, the people who dont want to be there will afk/dc until you kick them anyway. And you cant really add a greater penalty to a kick, because that is a surefire recipe for griefing.
This is why I said that perhaps a different approach needs to be taken with the "punishment" too.

For instance, people here and in other threads proposed the idea of roulettes locking to whatever duty is first rolled in a given day if they are bailed on, meaning they will either need to suck it up and deal with whatever they rolled or forfeit their roulette bonus for the day. At least something like that might actually start somewhat resembling a deterrent.