The reason is actually very simple. So, lets say hypothetically someone threw you down a pit filled with zombies and you, the mighty warrior that you are, killed all of them with you bare hands and climbed out a victor and everyone is like "OMG, that dude is the shit!!! He is the definition of awesome!!!' That's what its like getting to the top of the ranks in solo Ranked queue, you VS a bunch of zombies with your bare hands on a keyboard and a mouse.
this was a beautiful post.