Most opamps have emitter-follower darlington output transistors. Then they do not saturate, instead their emitter output follows the base with a 0.7V to 0.8V voltage drop. A darlington is two emitter-followers in series so of course each one produces a 1.5V voltage drop. Then with a plus and minus 5V supply the maximum output swing is plus and minus 3.5V.
Why do you talk about a 500 ohms collector resistor? A class-AB darlingtons emitter-followers output has no collector resistor.