It should be noted that the correlation between PAR rating and "good for corals" is not entirely accurate. PAR values indicate the intensity of photosynthetically active radiation, but independent spectrums are not weighted for their photosynthetic efficiency in particular circumstances. Although photosynthesis can occur throughout the PAR spectrums (400-700nm), certain organisms utilize different spectrums more efficiently, based on their photosystem and light-harvesting pigments. To say higher PAR value = better is an unwarranted statement. Spectrum is a VERY important factor to consider.
In relation to our hobby ....
The greatest coral biomass is located below 3 meters of water. Only the more resiliant species will tolerate the rigors of living in the upper strata of water. Below 3 meters, the upper spectrum is significantly attenuated. Hence, it is not implausible or illogical to suppose that over zooxanthellaes' life history, corals have become better equipped to utilize - say - 420nm then 650nm. Not all PAR spectrums are equal, but PAR values treat them as such.
The moral of the story is: do not treat PAR as the ultimate factor in bulb decision. Use it as a guideline, but realize it is only half the story. People seem to miss this point quite often.
Food for thought: if you shine a high-intensity red spectrum light (eg LED) on most reef orgnanisms, you'll get no reaction. This includes fishes, photosynthetic and nonphotosynthetic bivalves, worms, and corals. Now, if you shine a high-intensity BLUE spectrum light on these same organims, they react instantaneously to the stimuli. This anecdotal obervation is very telling.