That might have been true for a couple of years if you just compare pure computing power, as soon as you factor in build quality and compared it to Thinkpad X1s, XPS & Co you were in similar price ranges again. Or if you don't care about build quality, another classic is the high-res displays (and software support) which took the competitors years and some might argue that they're still not there.

Oh and there was also a couple of generations where Apple had pretty much kind-of exclusivity on Intel's newest CPUs and they were really only available in MacBooks for the first few months.