An AMD A10-4600m is a 35w TDP part, and is significantly more energy efficient than an i7, of which for Ivy Bridge there are only 45w TDP parts. (and yes, they eat more power in benchmarks) The graphics on die of the A10 w/ 1333mhz dual channel RAM perform just below a Geforce 630m. But a 630m is a 35w TDP part. Which means compared to the top end mobile AMD APU, a comparable Intel + Nvidia setup uses twice as much power for only slightly more gaming performance. On a note, there is a 65w TDP desktop APU part, which would be still more energy efficient than said i7+630m. With a 650m on the other hand, you can add another 20 watts or so, making the AMD APU a more pressing argument, and with the desktop part, you would have the option of 2133mhz RAM, and with such similar performance again with a cheaper overall system.
My guess is though, is it came down to business deals and community favoritism.