I think your correct, but most keepers have only 1 or 2 iguanid lizards, which making a "correct" mixed green salad would be easy and non time consuming. Zoos have thier (I hate to use the word, but can't think of another) "grunts" and volunteers who have all the time and resouces delivered to them to make these meals. I personally have found dry food to be a "godsend", because I can feed and water 40 enclosures with 100 /- lizards (I can't keep count anymore) in 2 hours.
The minuses in feeding greens to me are 1.Spoiling and drying of uneaten food 2. Runny feces 3.Time taken to buy greens. 4.Time taken to chop greens 5.Money spent on greens.
The pluses of dry food are 1.Uneaten food stays eatable for days 2.Feces are easy to clean pellets 3.I always have 5 gallon buckets of this stuff (Zoo Med)on hand and delivered. 4. All I do is scoop and dump in bowl and add either calcium or vitamin/mineral suppliment every other feeding. 6.It takes much more greens to equal in volume the amount of dry food that can be eaten.
I produce fertile eggs and healthy offspring. Since I am a business owner, I really am limited on my time I can spend feeding or cleaning, so I really need it to go quick for me so I can have time to enjoy these animals also.