There it is. No diet works for everyone. The science around this is ever-evolving and will continue to do so. Experiment and find what works for u, paleo, atkins, intermediate fasting, heavy lifting no cardio, all cardio, limited strength, light weights lots of reps, steady-state running, intervals. There is no ONE right answer.
But I guess on a message board, it's kinda fun arguing what's worked for you.
With all that being said, I have a friend who went to a medically monitored weight loss program. They had him on 0 carb with on protein shakes for 6 weeks and then started incorporating smoothies for the next 4 weeks. He lost a ton of weight in a short period of time.
Ya but a lot of that was probably muscle as well. Someone who is 320 lbs is not concerned with loosing pure fat, they just want to be lighter. As @Gunther said above, it really depends on what your goal is. I personally don't want to look like some featherless chicken, so muscle development is important to me.