Young man A.E. once explained that "technically darkness does not exist, only absence of light". How do you explain this?

Vacuum is the lack of any substance, silence is the lack of any sounds, dryness is the lack of any moisture.

Consider the "number" zero! It is neither positive or negative. It is neither even nor odd. Now negative one does actually exist and of course positive one does exist. But the number zero does not exist because it is the absence of value.
The same with darkness. It is the absence of something and null value. It is not negative light and it is not positive light, it has no light value and does not exist as far as light is concerned.

There is nothing technical about it.  If there is no light, then it is dark.  You are not showing how clever you are, just how dumb you are.

cause the absense of light is darkness