SO's Size?

Why are there so many posts about the size of their SO? It shouldn't matter what size they are. It doesn't matter who has average, above or below average. All that matters is the SO is loved for who they are and not how big they are. And honestly, as long as the size is perfect for the individual, does it really matter how big it actually is? They could have a huge one and not know how to use it and really hurt someone. Or they could have a really small one and rock your world. And of course there is everything in between. Size shouldn't matter to other people. 
-end rant.