Not surprising, making one good choice (avoiding sugared soft drinks) isn't enough to make a good diet, just like one bad choice doesn't make a bad diet. You could lose weight on the "Coke Diet" by consuming nothing but 10 servings of Coca-Cola every day.
It's simple math - calories in and calories out. There are "good foods" and "bad foods", but the effect of which food you eat makes less of a difference than how much food you eat on weight loss. Effect on overall health is a different story. A person on the "Coke Diet" above would almost certainly lose weight, but they would almost certainly suffer health problems if they stuck to it for too long. A lot of people give "healthy eating" advice as "weight loss" advice and vice-versa.
The real problem is the "Silver Bullet" mentality. The soft drink industry didn't cause this problem all by themselves and telling people to stop drinking Coke isn't going to do any more good than telling people to eat less fat did over the past forty years. If people used the low fat campaign to buy Twizzlers (a low fat snack), then the no soda campaign will produce equally horrible outcomes.