If relays deny requests for public events unless they have received an AUTH response, then it becomes a big problem. I won't be able to read a users public events from their outbox relays. 

 Oh, you mean, if all of their relays are AUTH relays, but not read-limited? Yes, that could be a problem. 

 What do you mean by read-limited? 

 When they use auth, but anyone can read the notes, who isn't blacklisted.