How is it is massive overkill? The total amount of structure is the same in both of the solutions. Only in the one you mention it has less gates. Same amount of input resources. Gates a free. 5 years from now kids will be making LEDs blink using vixie cron and a python script talking the GPIO lines of a 32 microprocessor and this is O.K.
I think you mean the ATMega168 and its power consumption is somewhat less than 0.0027W, while the BCM2835 is more like 2.5W, but regardless, I think you're defining overkill in terms of power, which is only one dimension, probably not the one the comment was referring to.
It's a bit like saying using a tungsten lamp is massive overkill in lighting a room.
