Once again-- you are expressing an opinion-- it is absolute in your opinion--
In some opinions-- it may not be absolute-- and a backup to the motors that prevent the screws from pulling completely through the shell would prevent a motor from coming loose and if they are tight, the motor will not become misaligned. So if some of the flyers want to use the backup plates as an ounce of prevention-- then it is not absolute to those folks. Maybe they can get it on the ground if the four mounting points failed-- at least the motor would not disconnect--- Cheers