and when did higher revs mean faster??

you just want to get high enough revs so that when you go up a gear you're still using as much of the peak of the powerband as possible (i.e. maximising the area under the power/rpm curve)

That is why one should shift gear past the "peak power" RPM - because you can get more area. Not because it gives you more "power" at a static RPM but because when you change gear between two RPM points which gains the overall best power at the rpms that u will use