[arp242]

But the question is, would Facebook still be around if they didn't "just ship this turd lol"? I don't really have any insight in Facebook engineering over the years and it's a "what if" type of question that's essentially unanswerable, but the answer to that being "no" is very plausible.

And Facebook really does have unique(-ish) scalability problems, and I bet rewrites would have been inevitable even with the best possible engineering, because who can write an application to deal with a billion users (2012, currently 3 billion) right from the start? When Facebook launched in 2004 this was pretty much unheard of, and even in today it remains pretty rare (much less 2012).