I think there are a lot more difficult problems getting solved in web development (e.g. in Big Data, scaling, etcetera) than in iOS development. I meant to say that it's harder to get started.
It's simple to whack up a HTML page with "hello world" printed bold on screen, yes. But then it's also pretty simple to do the same on iOS. If you want something quality then suddenly you have HTML, CSS, Javascript, PHP/Ruby/Python/Java, server tweaking, cross-browser hassles, graceful fallbacks and whatnot to deal with. It'll always be easier to create a crappy website than a polished iPhone app.
Not that I want to get into an argument about which is easier/harder. iOS is much harder for me but I have a 12 year head start with webdev.
The pain of doing web development for a maze of twisty browsers, all alike and incompatible makes iOS a "superior" choice in the sense that it means less headaches.
For me, it doesn't really matter which is easier or harder, but which has the best return on invested pain.
I am working on some solutions to get web pain down for our particular area of the industry, and as a result, I think the web may have a positive return on the amount of pain it causes. (FWIW, of course iOS has pain too, everything does, just using this as a measure of the relative joy vs. hassle of doing what's needed for business reasons, vs. hassle of having to deal with painful technologies metric.)
You don't have to make your web app compatible with every browser ever released—know your target audience. You can develop only for Mobile Safari—and, with a bit of effort, make your app run on Android, desktops, and even Lynx as well if you want.
Big data and scaling are networking problems, which are indeed hard. Networking doesn't have to be done in a browser at all however... Web development is strictly what happens over HTTP and it's not as difficult as several developers have made it out to be in this topic.
The parts that are difficult are so because of poor tool support or weak libraries (browsers, JS).
