> The backend of a high traffic web application (say 5k requests per minute) will have many highly technical problems that require deep understanding of databas

> The backend of a high traffic web application (say 5k requests per minute) will have many highly technical problems that require deep understanding of databases, transactions, scaling, networking, and knowledge of CS fundamentals to solve problems in those areas. i've worked on services with 1-2M requests per minute - most of them were stateless, and usually are (in a "typical" web company like big e-commerce apps, twitter, etc.) This doesn't mean they are easy to implement and operate, but they lack one huge source of complexity (in a mathematical sense, i. e. entropy) - the state. This piece is usually delegated to a database/middleware level and is spread over multiple more or less independent services dealing each with its own tiny slice of state. On UI (i.e. app with few screens, buttons and meaningful interactions between them - not a dumb statically generated blog) the complexity of state grows rapidly and there is no magic DB to shove it into. Because the state machine is the core of the app work - user interaction is literally a walking through transitions of state machine.