The criteria for getting monetized really aren’t that big. They don’t have to be that large, and most small to medium sized channels will usually make more from direct sponsors and supporters. But also, those are the creators working on the thinnest margins, and they definitely feel the loss of the YouTube ad money.
But the bigger issue is that demonitized videos just don’t get promoted as heavily. The reduction in reach is a major blow to small and medium sized channels, as reach is how creators find new supporters, and it has an impact on future direct sponsorship potential. Plus if you have multiple videos demonitized, you can get your whole channel demonitized.
Edit: Autocorrect believes “deminitized” is a word.