After I log off after multiboxing I keep trying to alt-tab to check my multiboxing irc, or my other window of tf2(Which there isn't a 2nd of either one) and literally feel like something's being ignored/missing if I Don't lol

But compared to Tanking well this really is not that tough. A tank has to pay attention to his own hp, each mob in combat atm, his position relative to his party/raid, the mobs' directions in some cases, and his party's hp/aggro as well(or the healer's mana so he knows to trinket/run like hell) vs. what is currently, thanks to everyone's work paving the way and programs such as keyclone, a fairly easy thing to do; once set up, you're basically running one uber char if you run a group of same classes.

For thoserunning mixed groups though I'd say it would apply as multi-tasking too...trying to tank, heal, and dps at the same time vs mobs/bosses that CC and actually require you to work to keep under control is hell