The Wikibase REST API currently does not allow getting the value(s) of a statement based on the Property ID - only based on the statement ID. People want to get data from Items based on the Property ID (e.g. P569 - date of birth).
Get specific data from an Item for an infobox-like view. A request could be "What's the date of birth of that person?"
Benefits (why should this be implemented?):
Access to data would match the intuitive way reusers think about it