It took me a bit of puzzling, but I finally figured out why the anarchic gang member who shoots Cyrus in The Warriors is named "Luther": he fractured the great gangland alliance by sowing paranoia, just as his namesake had split the Catholic Church in the sixteenth century!
Each gang was only allowed to bring nine members to the big meeting, but as we see, even fourth-rate gangs like the Orphans actually have many more members than that. So why is it that when the Warriors finally make it back to their home turf they are unable to call on any extra help?
In response to the above logic statement. Two possibilities to why. One many of the gangs before the climax went to Coney Island first and killed off the other members. Two, word reached to Coney that Cleon died, and they left leaving the 8 left.