"Eat your own dog food", goes the (rather unpalatable) mantra in Silicon Valley. The argument goes that, without your employees using your own products, how can you know for sure that they are something which your customers would want to use? Take, for example, the fact that Google's Eric Schmidt uses a Blackberry instead of an Android smartphone. How can anyone expect the company to have the kind of top-down commitment to greatness which is so often credited with making Steve Jobs years at Apple so successful, if its own executive chairman thinks another company makes better products? And failing to eat your own dog food is also a symptom, as well as a cause, of decline: consider what the difficulties Microsoft had in dealing with the incursion of iPods rather than Zunes into their employee's pockets said about the eventual victor of the MP3 wars.
But Facebook is in the unusual position of having the opposite problem: its employees use the site too much and too well. In eating their own dog food (and nothing but their own dog food), they end up completely unable to imagine how their typical users interact with the site.
Facebook's site can, if you let it, completely manage your life. You can make an event for everything you do, from work meetings to dinner dates; you can use its messaging client like email, right down to being able to take incoming mail to your @facebook.com address; you can use chat, status updates and photo posting to the exclusion of all else (so long Twitter, Gchat and Instagram); you can check in to your favourite restaurants, follow celebrities and even run a business from your page.
A lot of people use a lot of these functions – but how many outside of Facebook's campus use all of them? And how does that affect the products they make?
Take Facebook Home, a total conversion for your Android smartphone into a Facebook machine. It squeezes all of Facebook's services into your phone's homescreen - whether you like them all or not. Use Facebook just for photos and organising the occasional night out? The chat integration will not be particularly useful for your. What is you prefer to tweet good things you've read rather than post them to your wall? You'll have to change the default settings, then.
But the product which really couldn't exist without an overdose of dog food is Facebook Graph Search. That's a product whose advertised use-case relies on users "liking" their dentist. That might be normal behaviour for the people who Mark Zuckerberg hangs out with, but for most, it's just a bit on the odd side.
The reason why graph search in particular is such a flop is simple: the behaviour it encourages to use it is not the same behaviour it takes to make it work. If you want to get the most out of graph search, you don't have to post a single thing on Facebook – but your friends do. That means that simply launching Graph Search onto the world isn't enough to populate it with useful data, and so it's currently best for finding out awkward facts that people might not have meant to make public
Ultimately, Facebook's major engineering problem for the next phase of its life isn't about trying to make it easier and more fun for people to get information out of the site; it's about trying to encourage them to put it in. But that's a problem that they can't tackle with a company full of employees who are only too happy to live their lives on the social network without any encouragement.
Dog food is an important part of a company's diet – but eat too much of it, and you'll get sick.