In which case, so sorry...

Seriously, I can think of at least three good reasons. The first is that it is good to go out of your way to "eat your own dogfood" to catch bugs, issues, etc. The second is that it can be used for marketing, the PHB thinks that LDAP is a good thing, so the more times you can say LDAP mixed in with other good things, the better it looks. The third reason is interoperability. Multi-vendor would be better, but upgrading from one version of your product to another isn't bad to have. When you rely on rsync, you have to rely on file formats remaining absolutely identical. But build replication over LDAP, and as long as that works roughly as advertised, you get for free the infrastructure to roll out upgrades to a new version which might have changed all sorts of details of the internal file format.

None of these reasons are enough to say that I think it is the right choice to make. But someone might have had a valid reason for doing it.

Cheers,
Ben