In this context stateless usually refers to access to the wider system. When an html page loads, it has no state it can access right away, it has only raw data

In this context stateless usually refers to access to the wider system. When an html page loads, it has no state it can access right away, it has only raw data in the url and cookies. You are constantly having to recreate the state of the system as a user moves from one page to another. Design patterns like react are a natural fit for this system, its turtles all the way down. Applications on the other hand start their lifecycle as a singleton and because you can guarantee a parent child relationship from top to bottom it tends to facilitate design patterns with sharing of state more easily between pages.