That makes no sense. Trading desks at the banks are not dedicated to "efficiently allocating capital", they are there to turn a profit no matter what. What's good for a trading desk might not (and often is not) always good for the economy.
You say that passive investment provides no value to society because it provides capital for failed and successful businesses equally. But there you said it: it contributes capital to companies that will succeed. How is this "No value to society"?
>It's only more profitable than mutual funds because ETF's have lower fees due to special tax rules around rebalancing.
No, it's the other way around. It's because ETFs have been found to be more profitable on average than mutual funds, that it was heavily incentivized to invest in them. ETFs are profitable for structural reasons, because it's really hard to beat the market on average.