Which particular argument or arguments? You don't need to subscribe to the author's proprietary software to understand their valuation methodology. It can be gleaned by purchasing Brian McNiven's book, Marketwise for $24.95.
I agree the software on it's own is not useful if you don't understand what goes into it. Again, Brian McNiven's book explains it in detail and that book will give you a far better understanding of how to evaluate a business than any DCF model could.
I used to be a equities analyst and have used DCF's extensively. I found them to be inadequate and unrealistic. McNiven's method is far more practical and realistic.