When I bought my Glock G20 in 10mm, I also bought a 9x25 Dillon barrel. Because I would be using it mainly for heavy loads, I changed the guide spring from 17# to 20#. I just bought the 20# spring on a new captured stainless guide rod. Now my original captured 17# spring and fiber rod is a backup. Necessary, due to breakage, probably not. But neither is a buffer. I installed one of them, also. Good luck.
IMO it's a byproduct of the 1911 market.
Everyone thought they needed a FLGR for them, so a guide rod industry was born.
Next step logically, is to convince everyone else that they need a better guide rod too.:supergrin:
ETA: a makarov uses the barrel as a guide rod, typical of blowback guns.