Even if you want to deal 100% legally, you are obliged to bridge copyright law under certain interpretation.
You cannot copy some byte as defined by the state, as they belong to somebody else. You cannot copy them for yourself even, only certain cases are allowed. Yet to even reproduce a movie, you have to copy from your SSD, to your RAM, to your CPU cache, then finally to the CPU register. All what the computers does requires copying which a priori isn't allowed.
Ok, now you think I am being pedantic. Maybe that prior example was but the thing is that "what defines a computer" is ill-defined by networking. For example, let's say I have a NAS on my room and computer with another monitor on another room, and I "stream" from the NAS to the computer, did I break copyright law? Tecnically yes because I was doing the some processing on the receiving end, it was transmited in the form of byte (argueably a derivative work protected by copyright).
So with copyright you end up on a regime where what is a single computer is heavily restricted and to maintain the facade of what a single computer is, your have to actively monitor what the user is doing to restrict the world view to one where the networks of computers doesn't exist.