1) People advocating alternative therapies stirring up trouble
> "The campaigner and doctor behind MAIMES, Sarah Myhill, has posted YouTube videos setting out her views: “I liken it to child abuse,” she says in one that has been viewed more than 8,000 times. “This amounts to a form of abuse, because these people” – CFS/ME patients – “do not have the energy to defend themselves.” Myhill has published several books advocating what she calls a “naturopath’s” approach to treating symptoms of CFS/ME – one using a tailored combination of nutrition, rest and medicines. She hasn’t published peer-reviewed research on the efficacy of her approach."
This is highly suspect, like the group of quacks that started pushing "vaccines cause autism". It would be different if they were participating in the scientific process themselves.
2) People who have been denied treatment or disability accommodation because "it's all in your head".
To them, someone arguing that there is a psychological cause is not facilitating them getting the right treatment, it's someone preventing them getting treatment.
Given the interaction with disability benefits, having your disease declared to be in your head may result in the money you need to live being withdrawn. It's very high stakes.
3) Random internet cranks.
There are a lot of these, and someone who is unable to work and not very mobile and in constant pain is the ideal candidate for self-radicalising into a hate campaign. They have nothing else to do.