No company should ever buy the rights to something if they aren’t willing to provide a proper consistent experience to the user.

In the case of streaming services where you pay an ongoing subscription, specific content being removed is fine. In the case of a store where the user is presented with the idea that they are “buying” the content, being able to view that content in perpetuity should always be expected. Sony is to blame for not requiring this.

They don’t have to keep access to the content for new purchases forever. If Discovery wants to pull their content so anyone who hasn’t already paid for it can access it, fine. But if they’re able to say “you paid for this already, but too bad”, Sony and Discovery are both equally to blame and deserve the harshest criticism.