The legacy UserApp uses/used the SAML NMAS method to create an LDAP bind method. This is a powerfull method to do LDAP binds with the users' context when creating custom web applications that are SSO'ed with something else than NAM (eg integrated into OSP or ADFS).
For the moment, the SAML NMAS method is not planed to be deprecated, but at the same time it isn't added to the roadmap as a future feature to preserve.
In the event that the UserApp (since becomming a backend rather than a front-end), would not longer be using the SAML NMAS method, it is preferred for these custom applications to preserve this SAML NMAS method as a feature.