I disagree with this, a lot. It was a lot more than just mass marketing that Apple brought the smartphone. What they did was they turned the smartphone from a balky, failure-prone, buggy device to a device that, while it didn't do anything groundbreaking, it did what it did
very well. It does it consistently, and it does it simply, and it does it right. And that's what made more people willing to use it.
The first iPhone and iOS 1.0 was absolutely less functional than most smartphones out there, and I remember when it was first announced, I was one of its biggest detractors. Up to then I had been the proud owner of various Palm devices (since the PalmPilot 1000 and up to the Treo 750), Windows Mobile (up to the Samsung Blackjack) and Blackberry (going as far back as the RIM 950 and leading up to the Blackberry 8703c).
7 months later, I ended up getting an iPhone of my own. Not because it could do more than the other smartphones that I owned, but because it wasn't something that I would grow frustrated with, because it wasn't doing what it said it would do.
Every previous smartphone I owned prior had over-promised and under-delivered. I had Blackberries that silently deleted whole swaths of e-mails without my knowledge or consent. My Treo 700p, just to single one model of many out, had this knack for rebooting at least twice a day even when I wasn't doing anything with it, and then also for momentous events like receiving a text message. And my windows mobile phones would Bluescreen... that was a REAL kick in the pants.
So, it was common for me to swap phones every 3-6 months. I'd go from Palm to Blackberry to Windows, and back, over and over, losing a day or two of productivity each time I switched, not to mention the countless e-mail and contacts I would lose due to glitch x, y or z.
Now, I only upgrade about once a year.

And I can definitely say that I've never lost an e-mail, contact info or calendar date due to a hardware or software issues since I've being using iOS devices.
What Apple did was make sure the basics worked well before moving on to other things. Combine with a UI that worked well, I think THAT is what made it so successful, and what brought smartphones to the masses... not just the marketing.
And we can see that now with how the market is turning out. The Android developers
sorta get it, but it's the thing that gives them their market share (hardware diversity) that is also their greatest weakness in that Android is still very rough around the edges. Microsoft is getting it, NOW, and Windows Phone is a much better product than previous iterations were. Palm ignored the situation until it was too late to make up for old sins. And RIM is feeling that heat now.