There is no "ban" on peanuts or nuts.  If there was 5 Guys Burgers and Fries wouldn't be allowed to operate.  Believe me I would love to take my wife there for a burger, but walking through the door might kill her. 
The issue is that the odd cross-contamination can and will kill/hospitalize people.  After having spent way too much time in ER's because of accidental cross-contamination this move by McDonald's makes you go what the heck especially since they were one of the safest in the fast food industry. 
There are reasons most chain restaurants have an allergen guide in the back so the manager can double check a person with an allergies order.  No so much with the non-chain places where your relying on the staff to know the products they have.  So yeah eating out can be a life or death mine field depending on your allergy and the severity of it.