for a number of reasons:

  1. the system already uses a relational database to store most of the data it is very expensive to support another database.

  2. it means that some of the data is duplicated in both LDAP and the relational db causing data synchronization problems

  3. the system needs to be reliable, i.e. transactional, to the best of my knowledge LDAP doesn't support transactions meaning that we could end up with inconsistent data

  4. we use the data in reports