Suppose we enforce the following deck restrictions:
15+ cards: 2 star unrestricted, 1 3+ card
30+ cards: 3 star unrestricted, 1 4+ card
45+ cards: 4 star unrestricted, 1 5 card
60+ cards: 4 star unrestricted, 2 5 cards

This, so much this. When the NPC's have a 5 star, 2 3's and a 4, not having access to 2 star cards hurts. A lot.