Because the analysis is of what it does to the burden placed on artists (or those, really or purportedly, operating on their behalf) in the existing system. If the cost of a mistake is a ruined life, that side of things gets radically more expensive.
All of my analysis here is predicated on "if we want to try to make the existing system work like it is supposed to," which I will be the first to agree is not our only option; even in that restricted scope, my conclusion was "it's tough to say..."
Why? Aren't lawyers supposed to be professionals who are held responsible for their mistakes?
Filing false notices can ruin lives too.
PEs and doctors lose their licenses and/or have to pay massive malpractice judgments for mistakes all the time. Why not lawyers?