I will agree with what everyone is saying Re:
they dont need an anemone. but a few things that I disagree with here.
The Anemone suffers from frequent to constant irritation from the Anemonefish and it 'can't get away' from this irritation.
Some would call it stimulation. I keep quite a few anemones, and to use my giganteas (a species that is notoriously difficult to keep) as an example, seem to look very dismal in health until clowns are added. I attribute their sudden perky-ness and healthy appearance to the stimulation from the clowns. I will say that if the clowns are too large/aggressive in comparison to the anemone, then it could be irritation and not stimulation.
The Anemonefish does get mildly stung with sometimes minor observable conditions (when it becomes more noticeable it is called Hyper-Melaninization)
I think that most anemonefish keepers will agree that they see more hyper-melaninization when clowns pick an un-natural host like euphyllia, zoanthids, etc.. Or even an un-natural hosting anemone.
Although we (humans) attribute this a symbiotic relationship, it is better for both in the captive environment to go their separate ways.
To me this sound like you are saying its better to
not keep anemones together with their natural hosts. While I do agree that the clowns do not need the anemone. I dont think it is
more beneficial to keep them separated as your post sounds. I feel that they will feel happier/safer in a natural hosing anemone, whether its in captive environment or in the wild. After all, we are trying to re-create nature in our little glass boxes.
Disclaimer: I do recommend research and setting up the proper environment for anemones and their fishies that they host. I dont recommend plopping and anemone into any tank just to make clowns happy. As stated many times in this thread the clowns dont need the anemone