affordable smartphones had been around for years before apple made a smartphone.
furthermore, it never was even a market leader in quantities.
what was needed for the apple version, inventionwise, was nothing.
what was necessary from apples side was screen costs to go down enough and component costs to go down enough so they could sell you a 200 dollar device for 1200 dollars on a contract. that was the real magic of the first generation iPhone - selling a smartphone that lacked actual natively running apps, that had a lackluster resolution screen even for the time, for about 1200 dollars unsubsidized(yes thats how much a launch iPhone cost the people making 2 year contracts at the time).
a long rant about the american/global phones market at the time and how reading forbes ruins your global market leader company:
the american phone market was always twisted, especially in smartphone category - as for years yanks had been buying smartphones(palm treos, windows mobiles. blackberries) with price tags north of 1000$ without knowing that they were that expensive due to the network contracts hiding the costs of the devices(incidentally smartphone adoption in usa was low due to high costs of data plans and still is). rest of the world was dominated by symbian/nokia which provided smartphones with multitasking, web, etc. with phones in the 100 to 600 dollar price range.
you know what started the fall of Nokia really? it wasn't iPhone directly - it was iPhone being featured again and again on american magazines which made the board of Nokia think that they had lost the race and decided to aggressively "focus" on the american market - at this point symbian smartphone sales were still growing. as part of that strategy they decided to hire an american CEO, that american CEO then thought that symbian didn't matter and made a public speech declaring it dead at THE SAME TIME THE YEARLY SHIPMENTS WERE AT AN ALL TIME HIGH. the shipments had not even started to decline before the ceo publicly announced to not buy them anymore. the very same month they were at an all time high - moar money than ever from smartphone shipments for them! so why did he do it?
the board believed forbes more than they believed their own numbers of what people were actually buying globally. Nokia had put huge amounts of developer resources to pleasing american operators for no practical reason at all - as if at&t would have known what the phone needed to have in order to sell(they didn't know). hiring elop came during this focus on american market and american operators, because the light heads in the board thought that the american market was important for them(it wasn't, really).
thats such a huge amounts of fail that it's almost impossible to comprehend and bordering on sabotage, unless you look at the mindset at the people in charge: they were reading american business magazines and believing what was being written in them so they burnt about 20 billion dollars worth of company to ground and put a global brand leader name into an icebox for years.
iPhone as a device was more of a disaster for blackberry as blackberry was also a 1000 dollar device manufacturer that sold on the same markets to the same people, those markets being markets where people bought the phones along with the contract subsidized so that they never knew the real price of the device vs. service.
the biggest trick with the launch of the iPhone was selling it such a high price successfully - that was jobs magic with it.
the biggest trick with getting developers on board iPhone was deceptively simple: offer them a decent cut of the sales of the apps and ask _only_ 100 bucks to be a developer. simple.
but wait, for nokia you could develop and publish for free! well, kind of. if you wanted the app to be sold on operator sales channels and the like, you paid up your arse for it. if you wanted to use any of the more interesting api's you paid 700 bucks for signing - per update. if you wanted the even more interesting api's you paid nokia developer "club" fee, gave drinks to a bunch of people for a year and HOPED you would get the permissions.
then they were apis nokia gave only to middle management best buddies in exchange of bri.. personal parachutes(wifi sharing was built into the platform but the user interface for it was a 3rd party application. nokia ever gave the api to use to that one 3rd party developer, who asked money if you wanted to enable crypto. asking money of something that nokia built into the operating system already.).
so yes, the share of the profits of the apps that apple was willing to give the developers was a very fair one when compared to the general market at the time and the 100 bucks entrance fee was peanuts compared to general market(operator sales channels, mobile payment/licensing providers) at the time. they made being a developer being super cheap whilst they made buying the devices five times more expensive than an average smartphone.
also nokia could just as well have just hopped into the low cost android market - well, they actually did! they sold the nokia x line of phones very successfully in asia and emerging markets before microsoft put a stop to that. nokia x was the best - and cheapest - nokia I ever had - and due to various reasons I've had access to almost all nokia smartphones made between 2003 and 2013. it's not a matter of IF nokia could have made an android phone and went with that route: they successfully proved that they could make one very cheaply and that it would sell very well.. some people think thats why MS bought nokia, to prolong the windows phone by just 2 years.