When 306 hose and reusable hose ends were commonly use for fuel pressure and oil pressure lines, over time they have a tendency to develop cracks and leaks, especially under vibration and engine movement. So using a restricted fitting did lessen the amount of fluid loss if the hose failed.
With the use of teflon, with its higher fluid temperature capabilty and higher working pressures, not to mention its resistance to most all chemicals, hose assembly failures have become rare. So restricting the fittings is now common to dampen the pressure pulses for modern avionics sending units. Some have gone to using -3 hoses with .079 ID hose end stems without restrictors with excellent results.
Tom