Whats the craze and what do Carbon Fibre inserts do in a shoe?

Brief description and understanding of what a CF plate is about:

The plate spans the entire length of the shoe with curvature at the front to support the natural bio mechanical principles of running at the forefoot. CF within running shoes consists of a high modulus as the plate aims to remain rigid, instead of flexing, when running. CF plates involve increasing energy return through the runner’s gait cycle based on the energy storage mechanism it creates. The plate and midsole foam aim to provide high compliance (compression under force), stabilizing the joints and protecting the working muscles, whilst also possessing high resilience (greater stored mechanical energy). A reduction in energetic cost and increased protection would allow a runner to delay the onset of fatigue and therefore significantly improve performance towards the latter stages of a marathon.