Raider.io came into existence to basically make pugging higher keys possible at all.
Since you only have 1 try a need was created to be able to get an understanding of the level of play of everyone in the group before the run starts. This is different than raiding where you can just kick clueless people after a wipe and refill. Raider.io was created to fill this need.
Then a leaderboard for epeen.
That’s pretty much it.