By your example, companies should all be making computers that can only do one thing at a time, since, juggling two or three things would be prone to more mistakes. Its a bit difficult imagining not being able to talk on the phone, checking out reviews on yelp and downloading an app in the background since doing these things would "get less done, make more mistakes and miss more deadlines".
You get paid to talk on the phone, cruise yelp, and download apps ? Two questions
1) Who in the hell do you work for ?
2) Are they hiring ?
They are talking about people that do real work. Programming, generating reports, write ups, ect.
You realize that Android has only been out for approx 2 years after being released over a year after the iPhone, and they are already surpassing iPhone sales. webOS looks superior to iOS in many respects and now has backing from HP, a large enough company to throw money at it. I think the playbook can make some serious ground in the business field, and I'm sure microsoft is going to jump into the tablet arena soon (possibly with their new friend nokia)
I think it's a little arrogant to assume that in 2 years apple will still hold over a 65% marketshare "easy". This is going to be a fierce marketplace. I think in 2 years time Apple will still be number 1, but I think that everyone will be nearing them. Apple will be happy to be holding on to 50% of sales in spring of 2013.
So Apple #1 at 50% and the rest of the world at 50%. Out of the 20 or so 'competitors' they will have, which one will have the majority of the other 50% to be close to Apple ? Where will the Walgreens and Kmart tablets stand ?