Zend certified PHP/Magento developer

Why are quote and quote_item tables empty?

I’m working on an integration that reads data from a Magento2 database and the final aim is to send order data, products and the relation between products (line_item) to a third party service via API.

The database has thousands of orders, but none of them has relation for quote and quote_item, so I cannot reconstruct which products have been purchased.

I’ve been told by them that it’s normal to have quote and quote_item tables to be purged so it’s normal I can’t rely on that data.

I’ve read about it here, https://docs.magento.com/mbi/data-analyst/data-warehouse-mgr/sales-flat-quote-item-table.html but it looks that the best practice is to have the data purged only for abandoned carts and similar, not for confirmed and processed orders.

I need to know if the database I’m connecting to is using best practice or they are doing something very specific and unusual by deleting all quote and quote_item data.