Hearing so many horror stories makes me so grateful that I haven't had to come up against it with my own FM. From the word go, my GP has been brilliant with ordering appropriate tests, handing me the reins in deciding my own treatment plans, and pursuing ideas for interventions. My diagnosis also took months whereas some people have to endure years of being poked and prodded and verbally abused before they reach this conclusion.
Most of the criticism and denial comes from old-school medical professionals who haven't bothered keeping up with the latest research on FM, so they're attached to this idea that it's entirely somatic and related to trauma. (Even if it were, why do they think it gives them the right to be so cruel and dismissive when a patient is asking for help?) As for newer clinicians, they are taught "when you hear hooves, think horses, not zebras" and link that with the increase in cases of Munchausen's. They're fresh out of the educational womb and excited to diagnose on what can be observed, and FM doesn't fit neatly into that. Also cruel and dismissive.