[VLM]

Via analogy:

RDBMS = swiss army chainsaw, can do anything although maybe painfully and slowly.

NoSQL = 5/16th inch torque pre-set wrench for tightening sma connectors to 10 inch-lbs torque. Can't do much else, but its near perfect at its tiny little area of expertise.

On a meta level its a battle between hardware and applications, where app demands have (momentarily, of course) fallen behind commodity hardware ability.