It couldn’t. AFAIK Youtube still isn’t profitable for Google. Their business model depends on having a really low cost per user, so low as to be indistinguishable from free, and then making profit by selling their customers’ information/attention at a slightly higher price.
Any time you introduce any extra costs into this process, especially costs that can’t stay fixed while their income and growth scales (like server costs thanks to smart automation and Moore’s law) that hurts their bottom line a lot more then you may imagine. The need for human moderators would scale with the growth of the platform.
I agree with you that human moderation would be better then automated filters. I disagree that it would be a good solution. But even if it was a good solution, it’s never going to be applied by Youtube since it doesn’t fit into their business plan.
