I haven't checked up after any self-proclaimed multitasker and failed to find all tasks only partially brought to completion and in each case the ball was dropped. Well, you say, they're multitasking you derp!
No, they're rationalizing their inability to follow through and bring anything to completion without leaning on someone else to finish which is the cause of unnecessary added labor. At some stage before the end phase, they get bored, inattentive, impatient and more interested in the next thing.
Work: all sweet dessert but no less yummy supper in the world of the multitasker.