Against other human players this strategy only works to a point. Distance and supply isn't a huge problem for most human players once they understand the technique of fleeting with supply ships. And once Quantum Reactors are researched supply really isn't a problem at all.
Blowing up an opponents star system can be devastating sure, but given a large enough empire it's not a death sentance.
Star destoyers take a long time to build and a huge amount of resources to maintain. By the time you have them researched and built your opponent should be ahead of you in ships since you are spending a lot more on fewer ships.
Once you use it once they are going to protect their stars, so you have to knock them out very quickly. This requires a lot of star destroyers at the same time. And while you are setting this up you are vulnerable to a pre-emptive strike.
To do this against a human, it almost has to be a complete suprise, and you have to wipe out most of their systems in the first volley. Not easy to pull off.
Plus, it's not as fun as methodically taking planets one-by one from an opponent. Planning straetgy and counter-strategy. Fleets battles and what not.
Of course that Last point is purely my opinion.
Geoschmo