I have taken care of horses with just as bad condiion as the pictures you show, due to shoeing and poor management by a trainer. They all were wearing shoes.
I used proper diet (hoof problems or not) and hoof grease to keep them moist. No problems, all grew out just fine.
When they would go to the trainers, he evidently didn't feed like I did.
Funny, cause he promotes a feed. LOL