While I appreciate what you are saying, I think this statement is not really accurate if you look at the facts. I would not say "virtually any" because there are numerous academic projects that are now abandoned and whose creators consider a failure. So, semantically, "some" might be a better word in the place of "virtually any". In any case, I think you are underestimating how complex Airbnb's tech is. They have tons of banking regulations that they have to follow because of their payments and to think that their tech is "crud" is just a testament to how well they make the complex seem easy.