To quote the source, the following sites claim that the Nikons: D90, D5200, D3200 and so on will not meter with AI lenses.
From my understanding there must be some kind of sensor inside of the camera that measures the amount of light that comes in (kind of photoresistor). If that were true, all Nikons will meter with basically all lenses, so what is different that it doesn't work?
And why the AI lenses work with high-end models: D7100, D200,... etc. ?