It is not meant to save the doctors face. The very definition of FND is "doctors dont know what is wrong, but they acknowledge that your symptoms are real".

The point of giving it a name is in the second part. Its about explicitly acknowledging the limitations of medicine

There are actually specific diagnostic criteria for FND. The BBC article mentions that the young patient showed impairment in voluntary motor behaviors, but not in involuntary behaviors (e.g. reflexes). That is characteristic of FND. Similarly, there are clear ways to distinguish FND seizures from epileptic seizures. It is not a wastebasket diagnosis at all.

“FND”… I bet they need to exercise, eat a balanced breakfast, sleep more and lower stress.

That’ll definitely pause the rapidly progressing dementia and loss of muscle control in patients in their 20s.

When doctors have no idea what something is and aren’t willing to keep trying diagnostics and interventions, it’s always “hey maybe get some more cardio and go easy on the peanut butter cups”.

It's a diagnosis that's made only after excluding a wide range of other potential causes for the symptoms (like brain damage, structural abnormalities, strokes, seizures, MS, infections, ...).

It's not just a case of "we don't know", it's a case of "we've looked at everything under the sun and nothing fits".

Sounds like one of those things that needs more research.

What doctor claims that everything about the human body is known? Or that they can cure everything?

“Not otherwise specified”