The theory as I've heard it goes that youtube believes manual human review of videos is becoming increasingly necessary and creates a significant expense (hiring human reviewers is more expensive than algorithmic review). The less monetized channels there are on youtube, the less money youtube has to spend manually reviewing videos. And if youtube users all 'choose' to watch only a relatively small portion of channels, youtube users will be less distressed when smaller channels start complaining about being demonetized. If the vast majority of their users are only watching a handful of channels, youtube becomes more efficient and more profitable.

Therefore culture shaping and profit are not mutually exclusive. On the contrary, they both reinforce each other.

I don't believe this idea, but allow me to play devil's advocate.

>And I suspect that they want to make money even more than they want to reshape the culture into the image of what they think it should be...

Groups often do this to secure future profits at the cost of current profits. It would be to the advantage of YT to reduce costs by funneling as many users as they can to the same result, allowing for the reduction of dynamic elements within their structure.

It could be that they are juggling total lost customers with a total cost of operation and trying to achieve a more profitable ratio with cheaper/easier to substantiate channels/results

tl;dr : Google would be cheaper to run if there were only 20 results. Google would be #1 if they could keep their current audience happy with that style of operation, due to the disparity in income versus outward expenses.

Maybe some group of psychologists is discussing what channels to bar next that won't hurt the bottom line...

(but, like I said in the beginning , I doubt it very much -- it's just a fun exercise to imagine why they would want to destroy content)