I agree, but didn't realize they could turn an I7 into an I5, or at least I never thought about it. But it is a great explanation for why I5 is in stock and I7 isn't.
As for overclocking, I didn't mean you can't overclock, because you can increase the voltage, which Intel won't. I meant you are starting with an under performing chip which will limit what you can get out of it.
To me, overclocking is has been pretty much dead for a while anyway. You used to be able to overclock 30%, even as late as I7-2600k. But now Intel is wisely taking advantage of the headroom. The I7-4790k was effectively overclocked to 4.4Ghz by Intel, and there is no way your getting 30% additional out of it.
Plus they say "free" performance, then they buy an expensive cooler, or god forbid, water cool it. And the time you spend over clocking and testing seems to be valued at zero.