Also, remember I actually pay hard cash for Youtube (which embarrasses me every time I type it!) so the idea that they can't distinguish engagement highly likely to keep me forking over subscription moolah versus engagement highly likely to send me running for the hills when I actively use their provided tools to tell them "I HATE THIS STOP SHOWING IT TO ME" is a pure business failure. The concept that all engagement is good engagement may work on a platform like Twitter where the point is to rile everyone up into opposing war camps but is that really why people come to Youtube? Some people just like physics videos, or cooking videos, or video game reviews, or whatever...