It depends on so many things I don't know. Just a complete on / off switch on getting resources seem to cause problems on its own. There are other ways to deal with turtling.
For example on MOO you can make fortress planets, but it is at the cost of your empire size. You can't fortify everywhere at once, so the enemys hit where you are weak. If you do somehow manage to fortify everywhere, then your upkeep will cripple you and then the enemy can use special ship designs to crack your defenses. For while you can only bring the single planet's production (defenses) into the fight, the enemy can use their whole empire's production into starships to attack.