You're absolutely right. This is the method that what we teach in aggression/growl classes. It's the only method that you don't need equipment for so will work best in most unexpected situations. It sounds easier than it is though. Once 2 dogs decide "it's on", finding the back legs and grabbing them can be a difficult task. I have used this method with 2 very large, capable breeds and although I'm 4'9 and under 100 lbs. I did manage to stop the fight long enough for the owner to remove their dog, the one being attacked. It's also important to pull the aggressor off rather than the dog on the recieving end of the attack, and was able to do so without suffering a redirected bite. If you try to pull the dog who's being attacked away first, more often than not it causes the aggressor to up the fight and you can cause severe tearing wounds to the lesser dog.
If you're lucky enough to be carrying anything to startle the dogs, shaker cans, water, then I would of course try that first. The reason for the wheel barrel method is that it is the safest (not foolproof by any means) way to protect yourself and we've all heard of people getting bitten trying to pull two
collars apart.