For what it is worth-
My areas where rabbits ate the fans down to the rhizomes do not correlate with those where I had rot or other problems, so I don't think rabbit pellets are involved. Cutting the leaves has been an experiment: I left some uncut and cut some. Those cut were easier to clean up in the spring giving less chance of insect infestation. Those uncut were a bit messier to clean up and held more moisture near the rhizomes in the "dried" leaves.
Last summer at a house a mile away the owner ran over the entire iris bed with his mower cutting everything to around 2" and did it shortly after the last blossom. His blooms were sparse this year.

I cut back in the late fall to make spring clean up easier but not right after bloom.

That's what I try to do, also, Paul, and sometimes I even burn the "cut off' bed in the fall. The leaves, here at least, winter kill, falling to the base of the plant, and act as a mulch, holding in un wanted moisture, and acting as a "home" for over-wintering insects. Again, I'm not sure it really helps, but it seems to do them no harm, that I can see, and like you said, it surely does make the spring cleanup easier! Arlyn

They only wholesale cutting of leaves in the fall is on Siberian plants. Except for bearded plants which look like there is a problem no cutting of those leaves. The suggestion of comparing them to tulips or daffodils is a good idea. However those leaves dry up so you can replant the bulbs. I think a lot of suggestions of cutting bearded leaves wholesale started with 'neatniks'.