Give it 30 seconds of thought, and it'll be blindingly obvious.
"Google/Alphabet doesnt have to pay them for the content now."
My question, why do they keep using a platform that's screwing them over?
Yippee: -3. Evidently stating the emperors new clothes are his birthday suit is bad/wrong.
When a video is demonetized, only a small subset of advertisers or no advertisers can be shown on that video. If no ads are being shown then neither Google nor the creator are making money (and Google is spending money to host and serve the content), so really this is a lose/lose for both of them.
AvE has been dealing with this very issue, where he'd upload a new vid, and within an hour, demonetized. It would within 1 day go unindexed. And for those who don't know, the first 48 hours is when most views come in. So, no ads = no money. He figured out if you make the video unindexed, then it would be demonet'ed. Then he would argue, and monet would be turned on. And then he'd make it public.
AvE got sick of that, and moved to Patreon, and then releases videos telling people to install Adblocks to stop youtube ads. (Pateron's had its own recent scandal https://blog.patreon.com/updating-patreons-fee-structure/ - Ive been seeing quite a few artists and customers move away from that platform. Where will they go? Who knows.. I digress.)
But to a larger point, storage space is near-zero cost. Bandwidth over a video that's unindexed is ~=0. And if unindexed stale video happens to go away, aww gee shucks. Google keeps the mindshare as being the only videosite in town, and starves any upstarts with their monopoly of videosite/ad/search proficiency.
Tl;Dr: Google is a very bad actor here.
A bad actor will try to find the limits to your system 10,000 times. A good actor will give up and go elsewhere. When everybody loses the bad actor will gain more perspectively.
"Social Media", be it facebook empire, twitter, twitch, google empire, amazon empire...
They want mindshare. They want people to keep using it, millions of people. Because the bigger the number, the more they can use various ways to entrap people into those platforms.
People keep saying that a demonetized video costs - the trivial bandwidth and storage of a deindexed video is miniscule. Yet, making people think they're the only game in town is all encompassing. You deal with them and their games and give them content, or you go away.
And not only that, but when people put up videos, they're also giving Google/Alphabet free machine vision content. Which that is actually worth quite a bit because content's hard to just generate.