Because on this song, the music was written first, (not lyrics), written by Don Felder, and another Don wrote the lyrics second. I think another Don, Don Henley, followed the music of this song that Don Felder wrote and wrote the lyrics of the song.
Because the music that Don Felder wrote was not a typical rock or pop song in the US.
Barry states he wonders if Randy, Bernie and Don Felder will as he states "show up". Without Randy's and Bernie's incredible voices the harmonies that gave the Eagles their awesome sound just would not have existed.
By now everyone probably knows the 2015 event did not include the Eagles because Glenn was very sick at the time and unable to attend. Desperado and On The Border are my favorite Eagles albums!!
Because it was a very long, mysterious, dynamic song in music history.