The only reason for that is because the physical disc has the right of first sale attached by being physical item, and there’s no practical/acceptable mechanism

The only reason for that is because the physical disc has the right of first sale attached by being physical item, and there’s no practical/acceptable mechanism to prevent transfer of the license to someone else. Traditionally the whole industry has been fine with it as long as direct media copying was too hard for the layperson, especially since lending games around was like word of mouth advertising. Digital platforms change a whole bunch of these things.