The contention on account sharing is "robbing companies of revenue". It is not related to additional costs imposed on companies due to account sharing. A non-negligible number of people engaged in account sharing are enjoying real value from the service(s) they are not paying for and would pay for if they could not account share. Hence account sharing enables the loss of potential revenue. As stated in another reply, if a company sees value in allowing customers to share accounts, they can build provisioning mechanisms that align with their TOS as Netflix has done.