Not even that, I remember 15 years ago universities saying that people had 3 devices on average, yet today Netflix only allows you 2 on their basic package. Now, people almost certainly use more than that. If I can't move from one device to another conveniently, then what's the point of paying?
By all means, limit simultaneous access between devices, but locking me to so few is just punitive. Who wants to pay for punishment?