Address forms can occupy far less space when implemented this way, which is especially helpful on mobile devices.
Research suggests that single line implementation is more intuitive when accompanied by a type-ahead experience. If a user comes across a complete set of fields, they’ll expect to go through it manually, but a single field places a user in a search mindset, allowing them to select instead of entering their information. A search mindset has been found to give users more confidence in their entry, and their choice of retailer due to the investment in customer-centric technology.
Find out more about using separate or bound fields on page five of this guide: How to implement address validation.