Traditionally when a customer purchases publisher content on a platform, we grant them an entitlement to the content. This can be customized based on the kind of purchase. For instance, for subscriptions, entitlements can expire but for perpetual purchases the customer will always have access.
For Open Access content, we had to find a way to grant everyone access to the content on our platform, not just customers who purchased access. The entitlement access model did not make sense because not everyone who visited the platform would have an account (where we could add the entitlement), and customers expressed a desire to see Open Access content separate from the content they had purchased. So, we had to made changes in the content logic on the platform, as well as search, browse filters, librarian dashboards, etc.