I'd have to politely disagree with that statement, all seeds are packed with nutrition, macro AND micro nutrients, look in any health shop, all you can see are seeds (apart from all the pills, pmsl). What is our western culture based on? Agriculture? Bread, mainly? made from seeds? What's nutritionally good for us is usually good for plants.
Example of a good seed without it's enzymes........neem seed meal.
I've got a huge bag of hemp seed meal that I'm gonna start experimenting with. Any seed contains enough nutrition to grow a small plant without any other external nutritional additives.
When you think about it, all seed are meals are concentrated plant food, apart from the genetic function, that is a seeds only job.