the 5 mile limit was not dreamt up by the FAA, it is in section 336 of the FAA Modernization and Reform Act of 2012. Federal law calls out 5 miles.

As best I can tell, this is ALL from the federal law, not the FAA. The main point of (major) contention is the requirement that the model aircraft be "flown within visual line of sight of the person operating the aircraft". The FAA claims this mean the person flying the plane must maintain control with their own eyes, the AMA says a spotter is OK.

The rest of it is cut and dried in my view