That’s 100% not true. Read the rule
Targeting and Making Forcible Contact
With the Crown of the Helmet
ARTICLE 3. No player shall target and make forcible contact against an
opponent with the crown of his helmet. This foul requires that there be at least
one indicator of targeting (See Note 1 below). When in question, it is a foul.
(Rule 9-6) (A.R. 9-1-3-I)
Targeting and Making Forcible Contact to Head
or Neck Area of a Defenseless Player
ARTICLE 4. No player shall target and make forcible contact to the head
or neck area of a defenseless opponent (See Note 2 below) with the helmet,
forearm, hand, fist, elbow or shoulder. This foul requires that there be at least
one indicator of targeting (See Note 1 below). When in question, it is a foul
(Rules 2-27-14 and 9-6). (A.R. 9-1-4-I-VI)
It's only targeting on an established ball carrier if they lead with the crown. Defenseless player it would become helmet to helmet or forcible contact to the head or neck area. Read the rule.