Subscription based services, on the other hand, don’t have to care how much time you spend with them—as long as you keep the subscription. They don’t have to be evil to survive.
If subscriptions don’t have to be evil, why must ads be? You seem to be assuming advertising here means display advertising and are forgetting about things like cost-per conversion advertising where there’s not necessarily any value in keeping you looking at things, only at rarely getting you to look at the right thing that results in you buying something, which is not much different than getting you to pay to look at things via a subscription.
If subscriptions don’t have to be evil, why must ads be? You seem to be assuming advertising here means display advertising and are forgetting about things like cost-per conversion advertising where there’s not necessarily any value in keeping you looking at things, only at rarely getting you to look at the right thing that results in you buying something, which is not much different than getting you to pay to look at things via a subscription.