Because an MBA will realize that they're "leaving money on the table" and not "maximizing shareholder value" by selling ad free subscription services.
Subscription based services also require you to be authenticated and that enables fine grained invasive tracking. Something traditional media couldn't do.
If delivery costs were a factor then I shouldn't be charged $15 for an ebook with near zero distribution costs when a paperback was $5 before ebooks came onto the scene and introduced a new incentive for price gouging.
