Nationalist or states rights?

Why can't you be both, obviously there is a need for Federal legislation on issues like equality, workplace safety, air traffic etc. There is also the need for States rights to reflect the values of the people who reside in them, I'm sure people in Idaho disagree with people in Clifornia on more than a few issues foe example. That said State & Federal laws can and do come into conflict like California's medical marijuana initiative VS, Federal drug law enforcement but all in all both are needed in a democracy