If something is a known-known, you have to take personal responsibility when you don't take that thing into account and get bit. It's not appropriate to even mention some person you have not met as part of the reason a demo failed. Personal accountability it key in this industry, do your due diligence and events like were described will not happen.
Everyone dropped the concurrency ball hoping that was someone else's problem. Its the dev team's fault because everything is ultimately the dev team's fault. But it would also be great if it was fixed in ruby + ruby's ecosystem.