look, everyone is just chasing the original point around in circles.
the original question was can a light be too efficient, and the answer is, it depends on your goal. if you want to use it in a real world application where heat is a concern, then depending on your environment, yes, its possible to be too efficient, if you need the heat from that light to help maintain good conditions.
if you're trying to get the most par light possible at the lowest energy use, then obviously, no, a light can never be efficient enough.
all the rest of this is just people arguing their opinions.
it's been fairly well accepted that leds produce the same amount of heat at the same wattage, but it's not the same type of heat, and is easier to deal with in general.
you can argue anything else you want to, but those facts remain, and if you can't accept it, then you're never going to get how it works.
because Fu, you're wrong, and it's going to take an epiphany for you to get it.