How are they killing the anemone by not going into it? Host anemones don't need to host clownfish in order to survive in captivity. In some cases--such as if the clowns are too large or aggressive, or the anemone is too weak--they're actually better off not hosting clownfish. Clownfish can be rough on host anemones.
Aquariums in no way replicate the ocean, aside from containing saltwater and perhaps some of the fishes, corals, and other life that might occupy the same habitat in the wild. They are a comparatively infinitesimal quantity of water that moreover isn't influenced by tides, seasonal fluctations, spawning cycles, predators...the list goes on and on. Your clownfish may be in a good, appropriate habitat, but it's in no way a natural one.
Finally, it's a bit hasty to assume that the fish are permanently rejecting the anemone. Each clownfish is an individual. Some might take to a host right away. Some will do so eventually. Some never will at all. Your fish aren't "stupid" or reacting improperly to their environment; they're just not doing what you want them to right away. Have some patience and give them time.