No, they simply won't be. The cores tend to run at a slower clock speed, and even middle-end desktops are coming with powerful quad-cores, along with a hefty amount of RAM and sometimes a dedicated graphics card. If you build computers yourself, smart phones don't come close to the same amount of power.
It's amazing how far they've come, but even tablets tend to be a little more powerful, and they too fall well short of computers. One could argue at the price differences, but for raw power, it's not even close.