I see. Thank you for asking.
Here, 'single page' is about reducing complexity that often accompanies an object-add, object-edit object-view multi-page paradigm in OpenACS.
An OpenACS package that manages multiple objects would be expected to have at least one page per object. A page provides context for end-user, so design is a matter of user experience preferences and the amount of complexity a developer wants to dedicate to a page.
cheers,
Ben