Actually I'd call it less stable.
I'd call that statement crazy. Both companies basically had all their revenue tied to one product line at any time.
Those two based their existence on the business market, Apple generates a vast majority of their income in the consumer market. The consumer market changes quickly based on what is cool right now this of course is subject to change at any moment
Apple is doing pretty well in enterprise right now.
http://venturebeat.com/2013/02/26/a...activated-last-quarter-are-iphones-and-ipads/
What Apple has not done is to spread their revenue flow out.
Sure they have to a far, far greater extent than the two companies we are comparing them to.
If someone comes out with the next "cool" phone or tablet where does that leave Apple, it leaves them with a 70% reduction in revenue.
Which would still be how many time bigger than either RIM or Palm at their peak?
But back to your point here. Why would Apple lose all of their iPhone sales simply because another "cool" phone comes out? In case you haven't heard, Apple users are pretty loyal.
iTunes is great but not being monetized all that well, Mac sales while better than the industry can't keep Apple afloat alone. There is no "must have" in the Apple lSW or HW line up other than tabs and phones. This is there problem, then need a must have in every sector they compete in not just one.
All things are relative, I guess. Mac sales kept Apple afloat when the were selling 10-15% of what they are now.