I think unless you've been there with a physical condition and had to sit through numerous people telling you that it's all in your head it can be hard to really understand why someone like the OP could react the way she did to the form.
I don't have one of the conditions talked about but mine kind of mimics anxiety, fatigue, brain fog, nausea, racing heart, are some of the symptoms. I knew it wasn't anxiety I just knew it yet I'd go to the drs and they would increasingly talk to me like I was an eejit that just couldn't understand that it was anxiety. Finally a new GP from the US joined the practice, I saw her and straight away she said oh that sounds just like x, referred me to a cardiologist and I was diagnosed. It was a horrible time, I was so ill at times and all the Dr would do was suggest therapy or suggest a different anti anxiety med(I tried them because I stupidly thought when they didn't work they might go oh wait a minute maybe it's not anxiety), meanwhile I was scared because I didn't know wtf was wrong with me and nobody would help me find out.
I would have felt the same way if I went in about anxiety and they kept insisting it was my knee that hurt and I knew it wasn't but all they would treat was my knee.
That feeling is ramped up when people ask what is wrong with you and you tell them and they roll their eyes a little bit or you can just tell they are thinking 'well isn't it convenient that all you can do is lay about all day' like they think you're making it up too so you can doss about.
That was long sorry but I'm having a bad flare up at the minute and feeling pretty frustrated with my limitations.