They're just wrong.
I'm working with someone who's performing a major NetBackup migration, where hundreds of client are moving from one master server to another. After way too much looking, we discovered why things weren't working: the customer was using bp.conf files in Oracle's home directory. It was a quick way to solve the multi-homed problem they were having a long time ago.
This is the problem with distributed bp.conf files (and .nsr files in NetWorker). They hide out there in the middle of nowhere (since they can be anywhere), then strike when you least expect them to. Please don't use them. Figure out some other way to solve the problem.
In this case, we needed to put the NB_ORA_CLIENT variable in the Oracle backup script.
Please don't use distributed bp.conf or .nsr files. There's ALWAYS another way to do it.
Of course, you can comment on this entry if you think I'm wrong. 😉
----- Signature and Disclaimer -----
Written by W. Curtis Preston (@wcpreston). For those of you unfamiliar with my work, I've specialized in backup & recovery since 1993. I've written the O'Reilly books on backup and have worked with a number of native and commercial tools. I am now Chief Technical Architect at Druva, the leading provider of cloud-based data protection and data management tools for endpoints, infrastructure, and cloud applications. These posts reflect my own opinion and are not necessarily the opinion of my employer.