Facebooks engineering seems to have weird priorities. They seem put all their effort into crazy stuff like "Graph Search" whilst ignoring incredibly annoying issues like not having a basic search engine to find your own posts or having two week old posts showing up in the stream approximately 20% of the time. I'm guessing it is a lack of self discipline. Everyone wants to solve the sexy problems but no-one works on debugging the old year race condition that has been bugging everyone.