There are a few reasons: - FBJS is a specialized language that allows developers to create rich, interactive experiences within Facebook. - FBJS developers are familiar with the Facebook platform and how to work within its constraints. They also have experience working with the Facebook API, which can be helpful if you want to integrate your app with Facebook in some way. - FBJS developers may also be familiar with other popular Javascript frameworks such as React or Angular, which can be helpful if you want your app to use those frameworks.