Okay, but not really, right? once you upload a couple videos you become eligible to join the partner partner program. You just click yes that you've joined it and then you get the ability to select yes or or no for monetization. Certainly, WebMD is part of the partner program and is monetizing these videos on purpose, the same way that they have ads on the WebMD site. Having to sign in to use YouTube is not really that big of a bar. WebMD is making these choices, not YouTube.
https://support.google.com/youtube/answer/2475463?hl=en "YouTube may also place ads on videos in channels not in the YouTube Partner Program."
If you become eligible and join the YouTube partner program I believe there may be a toggle then, but for non partners it's completely up to YouTube.
And the forced sign-in of course never was controllable by creators.