Not exactly a ringing endorsement of the qualities of the poster as a software engineer. You'd think that for a project that might change the rest of your life, you'd spend some time reading up about back ups or source control.
Do you think the author had never heard of svn/backups until it happened to him?
On the contrary, everybody knows backups are necessary, the problem is bothering to actually do it regularly, especially on a high-intensity time of pre-launch. Personally I forgot to eat at times when working on our Kickstarter campaign video...
If the OP had walked onto dog poo just before entering YC's offices and had brought an awful smell to the interview (which would belong to the same category of small catastrophes), would people point out that you really should watch your steps??
Besides, isn't it possible (not necessary, just possible) that successful entrepreneurs are the kind of people who don't have time to backup their stuff, make their bed in the morning, store 10 days of food in the fridge and buy stuff in pairs in case one breaks?
Guess who is a lot more conscientious about backups and source control than he used to be.
Being able to write some code doesn't make you know anything about the rest of the system.