In so far as IBS is not a disease, then I disagree. It can be cured. It is not a true disease with pathological changes, but rather a syndrome, which most certainly can be cured.
Basically, you really need to get away from looking at health and disease from a purely medical model, which focusses more on trying to cure a specific ailment within the body and thereby bypassing the person attached.
The mind and the body are a whole unit and what happens in the mind also has a profound impact on the body and vice versa. The two cannot be separated.
What homeopathy and alternative therapies do generally is to try and treat the person with the disease picture. You treat the person with the symptoms rather than just treating the symptoms themselves and sometimes missing out the person. What happens with homeopathy is that you take a full case and you then give a remedy that fits the whole person and by treating the whole person you can achieve a cure and homeopathy also stimulates the body in the self healing process.
Just to say that I believe that a mixture of the conventional and the alternative is good and I don't believe that homeopathy can cure everything, but IBS is a case in point when it can. If pathological changes have taken place in a disease process, then homeopathy or any form of medicine cannot aleviate that, but it can help to reduce pain and anxiety and can work well in a supportive process. However, it is unlikely that pathological changes have taken place in IBS, so in that case, then homeopathy can have extremely good results and can be curative. It is all to do with boosting your immunity too and homeopathy can do this.
I hope this helps, but maybe you have to alter your thinking slightly and come round to the point of view that you are treating a person and not just a set of symptoms and that if you treat the person rather than just the symptoms, then full cure is perfectly possible.