We have so many "bandaids" but very few cures these days.
Perhaps AI systems will allow us to find root causes of these insidious diseases.
Yet, the main two treatment options are "workaround/hacks" or a very invasive operation.
There's only one [1] potential nobel "curing" treatment which is just gaining traction.
But innmy opinion with current technology, stuff like GERD or chronic bowel incontinence (due to mechanical failure of anjs sphincter) should be 100% solved.
The "why" is a little less clear, but it's likely a mix of genetic factors and environmental/infectious triggers. Plus good old-fashioned stress :)