The stack without GraphQL typically consists of three layers: the UI layer, the service layer, and the data layer. The traditional architecture often leads to an increasing number of endpoints, making it difficult for clients to iterate with changing requirements. Adding GraphQL introduces a new layer called the graph layer, which brings all data and services together into a consistent interface, decoupling the UI from changes further up the stack. This results in reduced surface area, allowing developers on both client and server sides to build independently, creating a more flexible architecture that enables clients to access what they need through a single endpoint.