Modern industrial agriculture has one outstanding advantage: productivity. Hundreds of acres of land can be cultivated with the labor of three or four persons.
Permaculture on the other hand doesn't allow for such productivity. Most people will need to grow their own food to some degree. That's actually great in the sense that food production becomes increasingly local, produced where it is consumed, in such a way that all nutrients make their way back to the soil in a cycle which has been broken by modern agriculture.
As another commenter pointed out, permaculture can seem unscientific at times. And it's perfectly fine. We all have different sites, climates, soils and experience, no size fits it all and it's often difficult in such circumstances to find the best solutions. Some will employ more unconventional ideas, as long as it works for them.
In the end, it will always make a lot more sense than planting a few hundred acres with a genetically engineering crop monoculture that can only survive with a constant supply of pesticides and fertilizer, while depleting the soil.
