I think THE ZONE being a problem or not comes down to whether the man is the pursuer or the pursued in the "friendship". I think THE ZONE is like the relationship "practice squad"; if no other team wants to sign you, it's better than nothing (i.e., social proof, connections on meeting her acquaintances, etc.) and by being around, you can hone your skill to either get past THE ZONE with this chick, or get with another chick.
That said, if a woman is desirable enough, there will always be weenies who will pursue THE ZONE in the hopes of getting past it someday, so by not pursuing, the chick will probably lose interest - although by staying aloof, it could have the affect of splitting the seam of THE ZONE. (Yes, I am ready for the new football season.)