Because it is easy and quick
Because it provides more services: anybody can access Eureka but only signed-in members can make a loan, request an item or access his/her Favorites.
To sign into Eureka, you will need your EU Login credentials (Council staff, member state delegates and staff of other EU institutions can sign in).
If you don't have an EU Login account, it's easy to create one by clicking on the create an account link
All EU institutions have the legal obligation to keep a central register of records of activities processing personal data (Article 31 of Regulation 2018/1725).