Different stablecoins provide different use cases in DeFi, which contributes to the prosperity of DeFi as a whole. Sounds great, but there's a problem, what if we want to trade those assets? Prominent AMM DEXs like Uniswap V2, Sushiswap, Bancor, or Balancer all use a method called Constant Function Market Makers (CFMM), or a modified version of it. This works great for normal assets but does not work as well for swapping between stablecoins (or assets that have similar prices like WETH/sWETH), because it results in a high slippage. It is unacceptable for people to swap 1 USDC only to get 0.9 USDT.