They take often a minute on applications, while other designators will look at LOR's to get an idea about the person when it comes to aviation it is about a 2 year path, they need people who are as close to a guarantee as possible to pass flight school, the ASTB is what indicates that. A person who is a Div 1 football captain, perfect GPA, LOR's from all types of people, and saved puppies but has 5's on the ASTB will have a low chance of making it, but he might be great at any other designator. The person that did nothing but went to college and scores 9's have a very good chance of making it. It is for that reason the person with the 9's will get picked up and the one with 5's will not, when it comes to a 2 year training program they have little room to take chances.
Also, LOR's are not a requirement for non-AD you can submit without them and experienced OR's won't worry about them.