Who determines the GOAT?

   After seeing so many discussions about who is the GOAT(greatest of all time) regarding NBA players, with names like Kobe, Jordan, LeBron, etc., I have been puzzled why some of the players of my younger days, such as Bill Russell, "Wilt the Stilt", and "The Big O", were not being mentioned in this conversation. Those that have brought up one of these players, were told that it was a different time.
   Now let's look at the NFL and how Tom Brady is considered by many as the GOAT. If questioned about this being one's belief, they point to Brady's 6 Super Bowl rings, the most ever,  and feel that proves it. Is that the barometer that we use? If so, let's look back to the NBA.
   Who has won the most NBA titles? Does the name Bill Russell ring any bells? He played 13 years in the NBA and was in the playoffs every year and won the NBA Championship 11 of those 13 years. Based on the above measure, Bill Russell is the GOAT in the NBA.
   Oh yeah, that was another time. The greatest domination period in NBA, was by the Boston Celtics, when they won 11 Championships in 13 years. That isn't discussed much, because "it was a different time". The Brady and Belichick show with the N.E. Patriots is the greatest domination in NFL history, but try to explain that to your grandchildren.