The problem with spend alone is that anyone who bought one ticket for more than $12K would become an instant 1K. 1 trip at ANY price does not make a Frequent Flyer, nor should it be sufficient to leap ahead of real Frequent Flyers that earned Silver, Gold, or Platinum status the hard way.

And no, the 4 segment minimum on United, United Express and/or Copa Airlines is not enough of a hurdle either. I've had many round trips with 6 segments or more.