Once Upon a Time they were keen to peddle a box for every room, each at extra cost. Same for portability -- they want to peddle service to multiple locations, not have you moving the one box around. That's their business.
Within the confines of my property, I suspect I could use one box, and string the cable around the house to pipe the signal coming
out of the box to the room of my choice. The only inconvenience would be that every set in every room would receive the same program, but that would also be true with one box moved around.
And why couldn't you simply move the box yourself from room to room? I have multiple cable outlets for the TV downstairs and the computer here in this room.
Reminds me of the old ploy by the phone company before "deregulation", when non-company attachments were "illegal" and they tried to force you to pay an extra monthly charge for every extension. I was always able to find enough good Western Electric phones for a couple of bux each at flea markets and yard sales, to put an extension in any room I wanted. I simply disconnected the ringer bell, since ringer current was the way they detected "unauthorised" extensions.
