[chibea]

The downside is that a bunch of processes started from one TTY doesn't get as much CPU as before. It basically shifts the scheduling granularity a level higher from processes to (interactive) sessions. Because that's what the question is: on which level do we want to have a fair scheduling? For a desktop user, processes have little meaning. Sessions, instead, are much more useful because they correspond better to his different tasks, for which he expects that the CPU power is distributed in a fair way.