> Does strobing the monitor wear it out any quicker?
No. LED's are semiconductor devices that turn on and off, much like the semiconductor devices on a CPU that switch billions of times per second. The monitor needs to turn on and off the LED's only 120 times per second.
LED's alse use unsynchronized PWM cycling for dimming, and using these precise synchronized strobes is actually lower Hz than that (but looks a hell lot better than PWM for me, due to the complete disappearance of motion blur)