It doesn't have to be. That's kind of the point. People are doing more on their smartphones and tablets than on their PC's. Why is that? Likely because they're finding free or very cheap apps that accomplish what they want to accomplish.
When you look at the cost of a smart phone vs a PC, a high-end smartphone costs more than a pc or laptop. It's only when you add the Microsoft operating system license and MS Office software and other software components deemed "must have" on a PC that the cost of a PC goes up dramatically.
Take that same basic PC that costs $600 or less, put the "free" Droid OS on it along with the Droid App Store and I think it'd be a hit. Buy the apps you want/need for pennies on the dollar compared to those for MS Windows and off you go.
Just my opinion of course.
I've been much more satisfied with windows 8.1 than I thought I would be. I'll admit that I don't use the tiles very often but I don't feel "lost" coming from windows 7.
My experience, and that of most people, is that, PCs nowadays are less expensive than owning a smartphone or any tablet. For a smartphone, one needs to purchase the device, or it comes included as part of the package that includes the device and the smartphone. Thus, a person could end up with a smartphone which, in reality, ends up costing thousands of dollars in the span of a 2-year cell plan. No PC nowadays approaches that kind of cost, unless one wants to consider that broadband is also needed to do a lot of the things a PC does nowadays. However, smartphones become obsolete a lot quicker than PCs, and thus, people might end up purchasing 2 or 3 or more smartphones, as opposed to just a single PC that lasts 5 or more years, and for which the OS gets support for 10 years or more.
When it comes to people doing “more” on their smartphones, it depends on what “more” is defined as. Recent surveys still point to internet traffic still being done mostly from PCs, by a large margin. That margin is considerably larger than the combined traffic from smartphones and tablets.
When one considers the overall cost for the lifespan of the PC, it’s a many times less than the cost of using a smartphone or tablet; and that includes the cost of the OS in the PC, which is supported for a lot longer than the OSes on Android devices or in iOS devices; in fact, there are iOS devices which aren’t being supported by Apple after 3 years; compare that to the support that XP and Windows 7 users get, which is for more than a decade. When the mobile OS stops being supported, most users will feel the need to go get the latest mobile device out there.
So, the reality is still that, neither smartphones nor any of the OSes, come even close to offering any real competition to PS or Windows devices.