Like the history of modern financial systems is that higher volume and lower latency yield increased returns. There's immense pressure to shave off milliseconds.
Right now DeFi is a mess of scammers, hype machines, and retail investors with no idea what they're doing; all on top of a slow, high-latency, wildly volatile, largely opaque set of poorly-connected markets: one per coin, really. There's tons of money that you can extract from that kind of environment, but it... presumably won't last.