Yes and no-- while geographic location can play into nomination competitiveness, a candidate still has to be scholastically, physically, and medically qualified by the USMA admissions board. Local military bases certainly make nominations more competitive, but so do many other factors like population density, to what degree a certain district is gerrymandered, etc. It has been said on this board that if one is applying to West Point, living in Annapolis or Colorado Springs helps compared to living in Highland Falls in the nomination department. If you live in, say, Northern Virginia, then you are going to have tougher competition for a nomination than someone who lives in Montana or Wyoming. I'm not disrespecting those who earned nominations from MOC's in Montana or Wyoming, I'm just laying down the facts.
Nominations don't just come from MOC's. There are service-connected Presidential nominations, Superintendent noms, VP noms, JROTC noms, etc. So while your location can make MOC nominations more competitive, it is not the end of the world by any stretch of the imagination.