Yes. He's gone into great detail about it in one of his videos. He talks about the flex Chrysler "built in" to the cars and how installing frame connectors makes them more rigid than they should be. Just to basically cliff note it.
Jesus christ.... that flex on my 62 is so bad the doors would stick when it was on jackstands... people seem to forget the goal of any auto company is to make **** as cheap as possible and hope it lasts 5-10 years..