".........but there aren't any reasons to integrate"

Joomla has a lot of features that could seriously add to the capabilities of Dolphin (like a store etc.) so I completely disagree with this assessment.
If it were used only as a community platform this would be a true statement, but it is short sighted to say there aren't any reasons to integrate.

I've been hoping for a WordPress integration for much the same reasons. That's also a community platform, but it also has very good see more quality store plugins, and classified ads plugins.