Timing wise, when 4.2 went live there was a 2 week window where only FCs could buy new houses(though people with personal houses could still transfer plots). After 2 weeks they opened up new purchases to players again. During those 2 weeks the restrictions in place prevented someone from picking up an extra FC house, after the 2 weeks passed anyone could purchase normally again. On the busier servers those 2 weeks saw a ton of FCs finally get their housing and most(or all) of the plots getting bought up before individuals could make purchases again. On the medium and smaller servers some of those plots have yet to be purchased 11 months later.