every connector that I can recall seeing has it were the plug (the part that slides 'over') contains the pin type terminal(s) and the receptacle (the part that fits 'inside') contains the socket type terminal(s), however this image listed from molex shows them the opposite way
molex connectors (resized).jpg
this begs the question of if there a right and a wrong way to terminate your connections or is it just a matter of preference?
looking at the above image, I can see the benefit of terminating this way since it may be a bit easier to get the extractor tool over both types of terminals
I also seen it where larger connectors (e.g. 3x5) have the terminals mixed, forming a "key" so that the connection cannot be made improperly. this was on connectors that didn't have a [keyed] configuration and there was the potential of accidentally mating the 2 pieces 180° off