That arguement always makes me smile. Purist say the buckeye coupling in not prototypical yet they are perfectly ok with a huge plastic D ring and ugly metal hook! Which, ironically, work more reliably than the more recent slimlined nem couplers...
A common misconception. The key is to use the correct Kadee, the standard #5 is too short for buffered stock. I body mount the #146 on long wheelbased stock suck as container flats and coaches and have no problems over tight curves, even when propelling stock.
The #146 is long enough that you can mount it flush to the buffer beam and it still projects far enough so as not to cause buffer lock. The added length also gives it a wider sweep to accomodate tight curves.