I've read of this new term called "Layer-3" or L3 for short. It's basicially a network built on top of a Layer-2 network which also relies on a Layer-1 network for security. If L2s are supposedly enough for scaling, why bother making networks on top of them? It doesn't make any sense. Unless L2s have the same limitations as L1s and developers need to create L3 networks to keep fees low and speeds fast.

Do you think L3 networks are necessary? If not, why? Do you think they're overhyped? Your input would be greatly appreciated. Thanks.