Yes, it's a stupidly overpowered tactic. Considering that sabo, protect, betrayal were nerfed to promote tactics diversity I don't see why this tactic gets a free pass. It has more range than sabo, lasts over twice as long, and occupies troops and springs traps, in addition to occupying defenses. Spam seven maxed out ones and watch the game play itself.
If they were really interested in diversity of tactics they would just limit the amount of sabo, protect, decoy, betrayal you can carry to two each but have them only take one space.