That depends on who the "they" is. Movie distribution companies want to maximize the value of their product, and that means marketing and advertising, exclusivity periods, product tie-ins and collaborations with different streaming providers. They know that they can get the audience numbers from anywhere, but the question is how much a particular streaming provider will pay over a competitor.

So movie distribution companies are certainly engaging in rent-seeking behavior–only you're not the customer. The streaming providers are.

(Reasonably good pun though)