Then all the people pirating your content via torrents or more likely watching something else would know what social convention they were flouting or submitting to.

Only on tech or creator related discussions are people even aware of the absurd idea that there is an obligation to watch ads or a requirement to subordinate your property, your computer that is, to some yahoo on youtube in order that he can earn money. Where no law is present and enforceable we cannot rely on social conventions we wish existed.

Just because you could make more money if people followed such a convention doesn't create any sort of obligation on their part nor in any meaningful way do terms and conditions bind them beyond being able to in theory take away an account they as consumers not creators don't care much about.