The trouble is apparently that Ads are worth more to these companies than ad-free subscribers.
Then they added postroll ads. Then preroll ads. Then midroll ads. With these ads I find YouTube unusable for any period of time.
It's this plus the fact that I get virtually no value-add with YouTube. I have to fight with its algorithmic recommendations more than I would ever want to if I were paying any money for the service. I also don't want YouTube Music and would like it completely removed from my YouTube experience altogether. My music listening is done through a separate universe using my own collection.
I would happily pay money for a service that could provide the videos I watch regularly with a reasonable recommendation system that worked for me. And it needs to be priced for basically what it is: network egress.
$100/12 = $8.33
$200/12 = $16.66
EDIT: I do wonder if the price point of youtube premium is too high to capture an audience that simply doesn't want ads but doesn't care about any other features. $6/mo is higher than the typical per-user ad revenue.