Just curious -- when you say "previously subscribed friends" -- do you mean people who have been referred in the past, but more than 60/90 days ago, and are now trying to return again?
Not sure if a previous referral disqualifies you, it doesn't say so, the only disqualifying factor listed on the website is you have been subbed within the last 90 days. In my case, my friend bought the game on pre-order, we even played beta together...he was never referred to the game through RAF. He quit 1.5 years ago so it's definitely been longer than 90 days. Out of the dozen links I posted related to this issue, i'm not sure if some people are trying to get a 2nd referral off the same person. There is definitely an issue here.