Comment by protonfish

I am not sure if I buy the "it's nobody's fault" explanation. From what I gather, what they built simply did not work, even though it was clearly feasible. They had a failure of engineering and could not afford to rebuild the entire app. I know nothing about the specifics of the architecture, but I do know first-hand that if using Rails as the basis of an efficient and high-capacity SaaS backend, it is the wrong decision.