As scientists we have to offer valid processes that can substantiate our claims. If the chief claim of this theory is that life can begin from a chemical broth of methane, ammonia, and water (among other species), we not only have to show that the chemical process is possible, but that the process could actually occur naturally - that is to say without having to radically alter the enviroment in which the products are created. Those factors, after all must be fully* representive of earth's early environment (*whatever that may have been from the model of your choosing)... And while earth's early environment was certainly volatile... I don't know of any place in the natural order where the pH levels can swing from basic to acidic then back again within microseconds, all while the pressure changes from subatmospheric pressures to 4 atmospheres, and while the temperatures rapidly change from 40 degrees to 142 degrees. Catch my drift.