Not true at all, and obviously im on this thread because im not neurotypical. ADHD is about misfunctioning emotional regulation and nothing to do with inability to form habits, as a matter of fact coping strategies is basically habits that work with disfunction. With ADHD I can focus extremely well, hyperfocus actually but not on the things that I find boring.
I'm strongly in the "near impossible to form habits" ADHD camp, so I agree with GP and disagree with you. Or, I guess, there are different flavors to the experience. Mine includes my mind actively resisting habit forming.
ADHD is also about executive dysfunction, which means I often forget or find it "too hard" (due to insufficient dopamine) to do the behavior I want to make into a habit.
But it's different to everyone, I have inattentive ADHD, you might have a hyperactive ADHD which means you struggle with emotional regulation and impulsivity far more than executive dysfunction and inattentiveness, so different tools work for you.