LEDs are extremely fast. The LED itself will add no perceptible smoothing. You could easily add a capacitor for low-pass filtering, but that would add cost so it's unlikely to be done.
Years later, it seems blinkenlights[2] went out of fashion and everybody started quantizing blink rates to 1s or 0.5s max. /sigh/ it's throwing out useful information for no good reason.
Laser diodes, on the other hand, are fast
I guess the phrase "LEDs are extremely fast" struck me the same way a pedestrian telling you "walking is the fastest way to get around" when you're stopped at a red light in a Lamborghini would