I assume the second post is sarcastic, but anyway.. if you look at Djokovic's opponents in slam finals he's won, it's Tsonga, Murray 5x, 3x Nadal/Federer. If you assign a player rating to his opponents at the point in which he beat them, it'd liekly come out to be higher value than the slams someone like Federer has racked up.
You can make it much more complicated, by quantifying the player rating in your own way based on player's record/peak etc.. but just the sheer talent against which he won his slams is outstanding.
Federer was outstanding in his prime and some of the tennis he played against Nadal was out of this planet, but a number of his slams he didn't have many good challengers. There's no way to quantify how Federer would've done if he'd actually had better opponents but in terms of how people actually did beating what they were up against, Djokovic did brilliantly.