Of course, there are exceptions when the building has not been divided and has addr:housenumber=20-22 for example. Then dealers could explicitly add their shop is located on №22(for instance). As for "If the shop later closes, the node can be deleted" - it is better to replace shop's tag with "shop=vacant" to have history of the node kept and later new date for a new shop might be added. I hope I would be understood, sorry if my English is poor.