If you DON'T give the engine an easy break in...
Um, no.
Easy break in: limiting throttle opening for X miles, driving it easily.
Hard break in: maximizing cylinder pressure. Riding it like you stole it.
Think of the difference between throttle-blipping "zing zing zing" and high-gear pulling from a low speed "whaaaaaa". That "whaaaaa" is what a hard break-in is about... that and snapping your throttle closed at high speeds instead of "throttling back".
An easy break-in means your rings don't get worn in properly, so they don't seal as well. You get more blow-by, less compression, higher oil consumption, and less power.
A hard break-in will push your rings against the cylinder wall harder, wear them to a better profile so they seal better, giving you more compression, less blow-by, less oil consumption, a cleaner combustion chamber, and longer engine life.