The Problem : Why not use existing Flight Controllers and Shields ?
While there are tons of popular Flight Controllers like Pixhawk and Shields like Navio2 none of them focus on pure Autonomous Flight. At the same time, A Standalone Flight Controller like a Pixhawk is too bulky and requires external sensors(GPS, Compass, etc...), making the drone more heavy and expensive. On the other end, something like a Navio 2 runs the AutoPilot Stack directly on the Raspberry Pi resulting in fewer resources for Computer Vision and Motion Planning required for full Autonomous Flight.