Captivity is an unnatural environment. In the wild, snakes are less likely to come back into contact with their own feces, thus reducing the chance they will be reinfected with shed parasite eggs. In captivity, they will be in contact with shed parasites constantly, even if you keep the cage quite clean. As a result, they build up higher and higher numbers of parasites in their bodies, which is what will eventually kill them. Severe weight loss is not the only problem that can be caused--parasites can cause a cloacal prolapse, and can migrate through the animal's body to sensitive organs, and even to the brain.
Consider that, if you believe positive thinking can make real changes, you would be going up against the will of other living things. If the parasite ARE there, you cannot make them disappear--they are ALIVE. Killing them that way would not be so easy--living things have the will to stay alive. It is best to find out whether or not they are there, for the health of your snake.
I agree that there is value to testing new arrivals and maybe running a fecal at the checkup every year.
But if you are practicing good husbandry skills and have treated all incoming animals for parasites, why a fecal every other month?