Interesting. But isn't this more like something (re-routing of text-messages) that happens inside compromised telecom service-provider? If they can hack the telecom-provider they don't need to get my phone-number from Facebook.

I haven't read the article in detail, but I think the point is some versions of this attack can be carried out by pure social engineering. Go into a store, claim to be you, talk your way out of giving ID, then get a new SIM card associated with your number and walk out with it. In this case, name+number is indeed helpful info for the attack since it doesn't involve any actual "hacking" in the computer security sense.