Apple was fined all over the world for intentional malicious software slowdown by different courts in many countries. Just google "batterygate". At this point this a proven fact that apple had been doing this. I am pretty sure they continue to do so. Why would they stop?
The slowdown occurs on systems that can't hold sufficient charge to reliably power the CPU to full anymore. If the battery can't supply the expected voltage, then the system simply shuts off. That is much worse than slowing down. This feature inarguably increased longevity—hardly what I'd expect from a "planned obsolescence" scheme.
They did make a mistake, though: they should have been up-front about it. They should have advertised it rather than hiding it away.
