He was not responsible. He participated.
You may give him too little credit; he seems to have been key to the successful landing:
When Armstrong noticed they were heading towards a landing area which he believed was unsafe, he took over manual control of the LM, and attempted to find an area which seemed safer, taking longer than expected, and longer than most simulations had taken.[67] For this reason, there was concern from mission control that the LM was running low on fuel.[68] Upon landing, Aldrin and Armstrong believed they had about 40 seconds worth of fuel left, including the 20 seconds worth of fuel which had to be saved in the event of an abort.[69]
Wikipedia Such unexpected last-minute split-second decision-making is precisely the contribution a pilot could make.
I didn't know that. Still, this doesn't get us anywhere close to justifying the typical extreme focus on a single person in thinking about this huge endeavor. Even saying that he was just a bystander, something that is false and so shouldn't be claimed, seems much closer to the truth than saying that he was responsible for the event.
The sad news broke tonight : Neil Armstrong, the first human to ever walk another world, died today. We lost him forever. He died before we could defeat death.
Once again the horror of death strikes. This time, in addition from wiping from us forever a hero of humanity, he wiped from us forever a memory that will never exist again. Never again will a human being be able to experience being the first to walk another world. That beautiful experience is lost forever too, along with all the memories, dreams, desires and wishes that made Neil Armstrong.
But thanks to him, humanity made a giant leap. We'll fill the stars and conquer death. The spark of intelligence and sentience will not extinguish. That's the best we can do to honour him.
Source : http://www.reuters.com/article/2012/08/25/us-usa-neilarmstrong-idUSBRE87O0B020120825