You would think they would be using the tactic anyway, fighting for their life and all.
You mean the scenario with the enemy dysons, right? It might make sense tactically to let the stabases tank, but since the ships' primary goal is to protect the starbases the other behavior makes more sense from that perspective.
Granted, it's actually more effective to let the starbases tank so the ships can accumulate overwhelming dps without getting shot at, but the smart thing for the dysons to do then would be to fly around and pick off the ships, etc. Or to pull back and wait until
they have overwhelming numbers. It'd be something of a behavioral arms race.