Why? It's pretty much clear. You have multiple locations, multiple IPA servers and
clients register to the appropriate IPA based on the DNS resolvers.
Even in the link you attached, the client is assigned to a location (Prague/Paris).
When you do in a cloud environment, obviously you want to automate this process. You
don't want to manually configure anything in the instance.
Of course there are ways to mitigate this (if there is no such feature) via a
configuration management tool or via cloud-init, but it defeats the purpose.