Now, where in the world did you hear that?
NEVER have i heard anything like that at all, in all these decades that i have been involved in rebuilding Mopar suspension parts, and brake systems.
Ever since 1980, when i discharged out of the Air Force.
And before the Air Force, i was an industrial machinist, and i know about Rockwell hardness test ratings for metal parts.
And i don't know what reason there would be for a hardness difference between a adjustment bolt and block, in a lower control arm.