It wound up this way because Youtubers want more money than AdSense and Premium can give them. They earn a lot more from sponsorships than AdSense and Premium.
Are you suggesting that Youtube squeeze out more money per view than it's currently doing? How do you suggest doing this? I guess one way would be to block people from using adblockers...
I'm not saying creators shouldn't diversity their income streams. My first comment in this chain was pointing out that Youtube isn't urging creators to embed sponsorships, which copperx seemed to think Youtube was doing.