Fitzgerald mentions all the names because he is trying to tell us about the type of people that come to Gatsby party. Most of which are very rich and have a very small interest in Gatsby and are just there to socialize. Most of the names listed are described as very self centered people, this is illustrated when Fitzgerald writes ” a whole clan named Blackbuck, who always gathered in a corner and flipped up their noses like goats at whosoever came near.”
The way they are described is very brief and the facts given about them don’t have any relevance to Gatsby, this makes them seem very insignificant.
Fitzgerald has created the illusion that Gatsby is a very important man.