Earlier quoted context omitted.
Am I missing something here? Paying cash doesn't prevent the opening of fraudulent lines of credit in your name. Equifax et al don't particularly care if you pay cash, they have some form of record on you either way.
I guess the idea is that if one were "off the grid" enough not to have a phone, one's details wouldn't be in their DB in the first place. That would make one's identity harder to steal, which would cause the thieves to move on to the next victim.
If there is no other identity using this SSN, then the likelihood of the fraudulent activity being dectected is low.
This is why SSNs belonging to elderly people, children/teenagers, and the recently deceased are of relatively higher value for a lot of people out there doing identity fraud.