The endless debate about Second Layers and their setups is so redundant. You need a base layer able to handle the settlements fast, cheap, secure. Everything in the history of humanity had to win in these categories. A Layer 2 should be like a Business, Layer 1 is at constant war with everything else in the world.
It comes down to this:
Faster - Cheaper - Harder
It was true for Persia, the Venetian Empire, and still true today in modern warfare. It's what makes or breaks an empire or a monetary system.