We've had quite a few disasters with humans in the loop. And humans are still in the loop, no one is banning them from the exchanges. As long as there is an arbitrage opportunity, why wouldn't someone take advantage of it?

The only thing happening is the low value brokers/traders are being taken out of the system and automated, just like people were made redundant in other industries. But for investors who like digging in and doing their homework, opportunity is abound. Everyone else can enjoy their standard index returns to keep up with inflation.

I'm just relaying the observations from someone like Mark Blyth on this topic:

https://youtu.be/TyxcholoFG8?t=45m30s