Listen. I'm not getting into flame war, but if you want to debate this, I'm willing to engage in rational debate.
My point, I believe, is valid. The difference between a computer and a phone, and an ipad and a phone is simple and blatantly obvious. So much so that I shouldn't even have to elaborate on it. It is that, almost everyone sees the necessity of having a phone for communication, where not everyone sees the need for computers or expensive tablets at home.
The smart phone revolution took phones and integrated internet browsers and always on connectivity. So people who otherwise, would not have ever sought those things out suddenly found that they just had them included in their cellular telephone.
And back to the financial reality of it. I've already stated this. Phones are rarely paid for in cash up front. I would wager that less than 15% of the phones purchased in the US are done that way. It's in an installment plan otherwise known as carrier subsidy that gets tacked on the monthly bill for 2-years, so people typically don't think about the true cost of the device. If they did, then perhaps, yes, they might opt for the computer and internet connection, but they don't because that $600 is not coming out of their pocket at once.
So, back to bigger screens. You have this person who suddenly finds out they enjoy browsing the internet due to the wonders of the smart phone. They don't have a comp at home, and aren't gonna drop money on a separate device when they already have a phone. But wait, it's time for them to upgrade their phone in a month. They can get a new phone with a larger screen and better enjoy their browsing on their phone. Why wouldn't they take more screen real estate?