Exactly. With phone number spoofing, all the scammer needs is the phone number of someone on your list. With social media how long do you think it would take to generate such a list, and to get propagated to every scammer?
It seems to me that phone companies can detect that, but they don't want to reduce the number of calls, do they?
And that's an awful lot of work just to cold-call someone to try to sell them insurance or whatever.
This has happened multiple times before, at least two separate incidents have made the news.
I'm sorry, this just sounds far-fetched to me. History seems to have shown that when hurdles are just a little too high, the spammers just don't bother.
This is mostly a US problem though. In Europe, the operators tend to be more strict on this, AFAIK.