Facebook is a very large company that uses lots of tools, and (apparently) encourage some degree of independence between its teams. So it is likely one or a few

Facebook is a very large company that uses lots of tools, and (apparently) encourage some degree of independence between its teams. So it is likely one or a few teams might be using this. I always take this kind of listing with a big grain of salt, because "company uses X" does not mean "company uses X in the majority of cases/primarily". Don't get me wrong, the lists are fine, they are just a bit less meaningful than what marketing copies want to lead you to understand.