I don't think they are going overboard. I think we are all different in what works for us.
About 8 weeks after surgery, I could eat just about anything I wanted in smaller portions. There are some things that agree with me more than others. If I just eat smaller portions and cut out the Snacks, I will lose weight because I have so much to lose. On the other hand, if I cut the carbs and greatly increase my Protein and Water, I will lose weight much faster. All of this was true before and after surgery.
Here is where you have a personal choice to make. You can lose weight faster or slower depending on which route you chose to go. Personally, I don't feel that either route is right or wrong. The one thing you MUST do is figure out how to be healthier for a life time.
I can eat the same things as before, but I also chose not to do so. I made a choice to use the sleeve as a tool to correct the bad habits that led me to this point in my life. Since I am not starving and having cravings all the time, I use it to make better choices. Before surgery, I ate a lot of fast food, drank nothing but soda or sweet tea, and could eat candy, chips, ice cream or Pasta as a meal (often my only 'meal' of the day). Now, I get in a Protein Shake in the morning mixed with my coffee. For other meals, I eat my protein first, veggies second, fruit third, and treats (breads, sweets, etc) last if there is room. I rarely skip a meal. I drink more water and less soda. I do have a treat most days of the week - half can of soda, part of a candy bar, some ice cream. I take my Vitamins. I move my body more. This is what works for me. I know I could lose a lot more weight if I was a more diligent, but I am not in a hurry. I am happy every day.