does luck exist in chess

If your opponent blunders its because they weren't thinking properly or they mouse-slipped. 

While you're right that the computer has an algorithm to select the most appropriate opponent, the opponent that ends up being picked could be considered luck from the observer's point of view. Imagine all the criteria in that algorithm - connection, rating difference, time in queue, etc. They aren't pairing based on opening preference, so if the criteria that gets me a match also gets me someone whose opening preference is something I am well prepared for, how would I not see that as luck? 

The fact that a strong engine can win 100% of the games against the World Chess Champion proves beyond a reasonable doubt that at that level there is no luck involved.  

I would contrast that with Backgammon.  It uses dice but in a 21 point match using the cube (which requires a huge amount of skill), the possiblilty of an average backgammon tournament player beating the world champion is extremely small but because of the luck factor it is possible.  I'm not a mathematician so I don't know how to calculate the elo used in Backgammon rankings.  

Backgammon engines are rated above even the human World Backgammon Champion and even though an elite player may win a match on a rare occasion against an engine, because of the luck factor the engines will never dominate the way they do in chess.

For those who don't know much about Backgammon, the longer the match using the cube, there is less luck and skill reigns.

There have been numerous chess masters who quit chess and became World Class backgammon players, among them are Bill Robertie and Paul Magriel.