It all depends on what you use it for. For the Gov.uk site, they don't need an FAQ, their design works great to categorize most of their information in a consis

It all depends on what you use it for. For the Gov.uk site, they don't need an FAQ, their design works great to categorize most of their information in a consistent pattern and I agree, they don't need one, it worked great for me. However, dealing with complex datasets that can't be categorized well (like some data can exist in multiple categories), or dealing with multiple apps and multiple platforms, things goes chaos and the Gov.uk's design may not work at all. As for folks who mentioned search, search technologies are not by default accurate like Google. They require a LOT of work to get it right and more likely to fail than work the more complex your datasets get.