Jen Brea, on a big reason for the lack of progress:
"It's really hard to find an answer for something, when you're not looking."
An analogy I like to use is you cannot diagnose a brain tumor with just a stethoscope. You need the right tools. One of our big issues is, I think, that until relatively recently the high throughput gene and transcriptome sequencing, and large scale mass spec, plus who knows what else, were either not available or too expensive. That changes over time. When the right technology comes along we find answers. It looks very much like we might now have the technology to unravel the mystery.
Yet its also the case that three well known, well understood, widely taught, and usually available (though with travel) tests were developed in the 1940s and are applicable to ME and CFS. I am willing to bet that only a small minority of 1% of the medical community even use them, or know to use them, in ME and CFS. They are still using those stethoscopes to rule out brain tumors.