I'd say that it is the internet in general that has a spam/scam problem. Due to bandwidth costs, which apparently only Google is able and willing to subsidize, YouTube is basically the internet for videos. Many opinions I read about YouTube do not consider this point and treat it as just another website. But for me, making Google responsible for whatever is posted on YouTube is akin to making ISPs responsible for whatever is going through their switches.

YouTube has a lot of problems, but I personally have no doubt that its existence is a net benefit to humanity. Calls for tighter regulation (or breaking Google down), which appear to be more and more common these days, make me wonder if would even have an alternative if YouTube went down. It is easy to take it for granted.