Retirement tax questions

Well after doing more reading other replies to these kinds of questions I am finding multiple things like this-

"The proper way to file missing Form 8606 is attached to Form 1040-X. Form 8606 can be mailed by itself only when you are otherwise not required to file a tax return."

and

"If you mail 8606 alone, IRS will send it back to you."

 

So are they wrong?