Sure, but why would I, as an entity buying advertising space, pay the same amount when YouTube is just going to try to show them to people who are asleep, that can't see the ads, and thus would have no effect anyway?

Your question boils down to "If I was buying a product from a company, and they made it worse, why would I pay the same price for it?"

Because YouTube has a functional monopoly on online video advertising in a huge number of markets.

Enshitification is not just for YouTube's viewers and creators.