On the contrary, we excel at it by pushing things 'down' when we have mastered them.
For instance, driving and talking to a passenger, walking and thinking about something and so on.
We are so good at it that most of the time we don't even notice any more how many things we are doing at the same time.
The only time we are not multitasking is when we are really concentrating on something difficult, usually problem solving or learning a new skill.
In my experience it depends on the amount of processing required. If I'm driving a straight away with traffic going mostly the same speed I can hold complex conversations. As soon as something happens on the road I drop the conversation until my attention isn't needed on the road anymore.
It's an amazing mechanism. Animals can do it too, birds can sing 'on the wing', there are lots of other examples.
Fascinating stuff.
That it can be done doesn't mean it isn't complex. It is.
And by "stability" I didn't mean the phone/tablet constantly crashing, I meant having inconsistent performance. Once you get into multitasking, everyone and their brother is going to have some really "good" reason they need a service. Some of these will always perform well, some wont.
>Multitasking is useful because humans are multitasking.
Humans are incredibly awful at multitasking.
>Single tasking computers are pretty much done for, multi tasking is the norm, not the exception.
Computers sure. But this is an instant-on consumer device. I think the use cases for such a device are different enough to warrant at least consideration for a different kind of OS for them.