Not to future students of genealogy it isn't

With so few people having their children baptised and many couples not bothering to get married these days there are few other records that are accessible to anyone trying to track a family tree. The census only started in 1841 and has been taken every ten years since in most countries. To get back beyond 1841 one has to trawl parish records as these are the only reliable source of Births, Marriages and Deaths (Registration, by the State, of these events only became compulsory in 1838) Given the number of parishes there were (and still are) this is a difficult undertaking without the invaluable information of family's locations, birthplaces, ages and relationships that the census records contain. It has taken me some 15 years to get back to the 1540's on both my Mother's and my Father's side of the tree via Parish Records, many of which are still held in the churches/chapels etc. The bit from me back to 1841 was the work of a few days on the internet. The rest of the time was entirely reliant on parish records, gravestones and manorial rolls.
OK that may be a selfish reason on my part but Nectar Card records (and similar) would not be of much use to anyone tracing their family tho' if the records of these and their use are kept they may be useful to social historians.