This brings back memories of when I was learing to drive a car in the late 70s - I remember my father telling me to use the brakes instead of shifting down as brake shoes and pads were easier to replace than a gearbox or clutch or both. That to me was a good argument at the time, in those days clutches seemed to wear quickly and a change of gearbox was expected. I think things have changed.
Sorry back to bikes - Aye I use my brakes to stop rather than slow down, much prefer to give the engine a blip, change down and let the engine do the work.

As far as keeping a bike in the power band - it depends what is meant by that - do they mean at the peak of the power band? If so that is crazy imo. Keeping the engine in the power band to me means - don't labour the engine and you don't need to take it to the red line as the max power is below that - just common sense.

__________________
Work hard, rock hard, eat hard, sleep hard, grow big an wear glasses if you need em.