IMHO, brushing may take care of some of the bacteria/toxins issues, and stimulate the gums, but there are other benefits one gets from pulling that you would not get from brushing. I am referring to the mouth exercise part. Yes, pulling is harder, just like running or walking is harder than sitting in a car.
To diverge for a moment:A while back I got myself a little gadget from Japan, it's called a lip trainer. I got it because I have sleep apnea and had problems getting used to the Cpap machine. The principle behind the lip trainer is that you insert this oval shaped firm plastic ring in your mouth and pull in different directions on the little string attached to it, while at the same time pulling back with the lips. It's amazing how the facial muscles incl. lips, neck, jaws, tongue, cheeks, back of throat get exercised! Very invigorating. Because of this exercise, all these muscles start to firm up!As a result people get help with snoring, sleep problems, level of energy, digestion, gum and dental issues etc., plus a firmer, younger looking face! Plus, because nerve endings and muscles in our mouth are closely linked to the brain, there is supposedly also a beneficial effect to the brain.
The first time I did oil pulling it reminded me very much of lip trainer exercises, just easier and more pleasant. So, I certainly would suggest don't overlook the benefits of the exercise part of oil pulling, although it seems no where to be mentioned.
wishing you health, wellnessyoga