Other frameworks are too design opinionated and heavy. They're great for prototyping but every time you start a real, front-facing, project with them you have to overwrite lots of designer styles that do nothing to add to the functionality of the website. That costs developers time and money. Responsive BP has been built with that in mind. It is the result of thousands of hours of real, client driven web development and testing; specifically developed to be as lightweight as possible to prevent the need to undo styles set by the framework itself and allow developers to write efficient code and lower costs.