This is a very good and important question and deserves a good answer.
The main advantage to using a bore guide/throat saver is to prevent wearing the throat with the cleaning rod. throat erosion is one of the main causes of accuracy loss.
In a perfect world nothing but the brush or a patched jag touch the barrel. a throat saver helps minimize this ware, increasing barrel life. It is the same problem when a rifle is cleaned from the muzzle end (The crown gets prematurely worn)
I use the largest one piece rod possible to also help. (They are stiffer that a 22 caliber rod and with no joints that could catch on the throat they also help).
There is also a benefit to starting a patch correctly and easy using the throat saver.
Once you use one you probably will never go back to cleaning without one.
Just my opinion
J E CUSTOM