There is a world of difference between physical and informational security, so it is an improper analogy.
First, it is possible to perfectly defend (and conversely, a vulnerability means one is entirely vulnerable. Don't confuse mitigations that affect the probability of being vulnerable with actually being vulnerable. There is no middle ground as to whether something is secure or not, it is a binary proposition!)
Second, attacks are practically free and untraceable. And all the status-quo anonymity-destroying attempts cannot actually change this, as making "network identity" trusted would mean changing every system's attack surface into every other system - eg break a single person's credit card and use Starbucks wifi.
First, it is possible to perfectly defend (and conversely, a vulnerability means one is entirely vulnerable. Don't confuse mitigations that affect the probability of being vulnerable with actually being vulnerable. There is no middle ground as to whether something is secure or not, it is a binary proposition!)
Second, attacks are practically free and untraceable. And all the status-quo anonymity-destroying attempts cannot actually change this, as making "network identity" trusted would mean changing every system's attack surface into every other system - eg break a single person's credit card and use Starbucks wifi.