I know that you are focusing on Ethereum based DeFi but it would be nice to explore the first blockchain to introduce decentralized exchanges, pegged assets, user issued assets (UIA), etc...with the most scalable consensus algorithm (DPOS). I am talking about Bitshares.
It would also be interesting to see why that first attempt at DeFi (years before ETH based dApps) did not have the success it could have had.