Earlier quoted context omitted.
I am similar unclear on where this supposed bright line sites but to try and steal man your argument a bit is it possible you looking for the distinction between excludable and rivalrous goods?
Just reading through, the distinction seems pretty obvious to me. It doesn’t reinforce several of my ideological perspectives, even contradicts some, but the distinction is plain as day. Physical things are subject to the laws of physics (can’t be in two places at once), idea “things” are much more ephemeral and thus much less restricted by those same rules (an idea can propagate basically infinitely and be “had” by…
The creative effort comprising time and attention that goes into bringing a work into existence is rivalrous. That's what IP law aims to protect/reward. People can insist on pretending not to understand this every time the argument comes up, but it's at their own peril; the world is not going to undergo IP reform as a result of anyone misconstruing or misrepresenting the issue as if it's really about whether or not person A is deprived of their copy of work Z when person B makes a copy of Z for themselves. It's not and never has been. It's about encouraging creators by offering protections in the hopes that doing so will lead to more people opting to create.