We live in the age of dynamic clocks where modern performance-oriented CPUs try to optimize both performance and power efficiency at all times, so for the vast majority of users, it's both a lot faster and a lot more efficient to do things this way, while enthusiast parts still allow a lot of manual control to squeeze out the last few percent. I've had really good luck in my past few builds just getting very high-spec RAM and running XMP / DOCP profiles with a small FSB OC and letting the multipliers do the rest.