Well of course ADHD is overdiagnosed in some areas, much like many other disorders are. It's why people spend years taking medications that don't suit them, and then realise their problem was something else entirely. Doesn't mean that the ones who have been diagnosed properly should be disregarded because these cases exist.

ADHD gets the shitty end of the overdiagnosis stick simply because it has very similar symptoms to various other psychriatic, neurological and physiological disorders. Much like CFS, a doctor will only really consider ADHD if there is literally no other explanation for the symptoms. Good doctors will take the symptoms seriously and test for literally everything they can think of before assuming it's ADHD, bad doctors will put it down to an idiopathic disorder and send their patients off with medication without looking fully into it.

Again, ADHD only gets the most gripe because of the exact symptoms and the medications used for them. Those who don't understand chemistry will immediately assume people with ADHD are speed or meth addicts after hearing the word "amphetamine" or "meth" from methylphenidate. Anti-anxiety pills and antidepressants don't get the same stigma because they're meant to calm and stabilise panic attacks and poor moods, whereas psychostimulants are considered bad because they're stimulants.

It's just another uneducated opinion in the guise of a scientific study, and the sad thing is that most people will believe this at face value instead of looking for the source information to make their own opinion on it. Everyone can read the paper, but few choose to read the actual findings since most of the "published" stuff is simply overblown cherry-picking.