What about subscribers using netflix at their home and their office/vacation home. IP addresses restrictions would cause mayor issues with those consumers.
It shouldn't be a problem unless you plan to watch at home and at the office/vacation simultaneously.
Where it will be a problem is if people use multiple ISPs/cellular data providers at the same time.
e.g. Dad on fibre, mom on MTN and daughter/son on Vodacom. Three people in the same household but each with a different public IP address.
That would be the exception though as most households with uncapped Internet use a single ISP so they'll be connecting from a single, dynamic public IP address.