I think it's difficult first of all because it isn't a common condition, which equates to there being a smaller pool of specialists that fully understand the illness. The first diagnosis was in 1915 if I'm not mistaken, so until then if you had CD, you were in bigger trouble than any of us now. I'm not bragging about Cleveland, but it serves as a great example. Between the Cleveland Clinic and University Hospitals, a pateint has at least 20 top-notch male and female cardiologists to choose from. I'm talking about specialists that are the best in the nation. That's a fairly large group of doctors that fully and completely understand cardiology well enough for any patient to feel comfortable putting their lives into their hands.
Ere-go Crohn's Disease: there are 2 top-notch GI doctors between the same two major hospitals in Cleveland who specialize in Crohn's disease. There are plenty of GI's here, but once they get any indication, not a diagnosis but merely a suspicion you have CD or UC - boom - off you go to one of the two specialists - and you sometimes have to wait a long time to see them, and buddy don't cancel your appointments!
So with Crohn's disease not as common, and relatively new in the world of medical problems, fewer professionals understand it, so diagnosis is not as easy.
The next factor is that it's an autoimmune disorder which means it affects multiple organs, body parts, regions, etc. Autoimmune disorders are the most difficult diseases to diagnose in the first place. Why? Because they are "non-pathogenic". There is no distinct external source of the symptoms which can be isolated. Nothing can be taken out and grown in a petry dish. No bacterium, no virus, no dog bites, not caused by obesity, no poisons. Nothing. Just a hosed-up internal set of immune system controls.
So maybe the immune system decides to attack the digestive system one day and a person gets poop all over and every living stomach symptom like we have for three weeks. But maybe afterwards, the person starts getting tremors and twitches which get progressively worse over a few months. The bowel symptoms might ease but still be in the background, but suddenly neurological symptoms become evident. Many Crohn's symptoms might be there. But Crohn's doesn't have a neurological component that would manifest in worsening neuro symptoms.
But there is an automimmune disorder that will attack the neorological system: Multiple Sclerosis. MS can also cause severe bowel difficulties. None of us understands autoimmune disorders well enough to predict how any one autoimmune disease can onset or manifest. Some Crohn's symptoms could actually be a part of an onset of different autoimmune disorder like MS.
All of us are probably in the best place in time for having IBD, but it isn't near a complete picture. I've been told by a couple doctors that more is known about effective treatments and cures for depression and mental illnesses today than for Crohn's Disease.
I'm convinced it's not anything purposeful that a diagnosis is hard to get. I believe that Crohn's disease is just very difficult to diagnose for now. Unfortunately, that translates into additional suffering for us.