This is all about "addons" like widgets etc.
Think Joomla, You have tons of extensions whereas D7 has very few. Joomla is more complicated than any Dolphin versions. still it can be modified to anything just by adding extensions.
say, i install joomla and browse the extensions and pick 15 "music" related extensions and in a week i own a music community. where as Dolphin's output is restricted to "Social community" and theres no way you can focus it as "something see more else"(a school website, a retail store" etc. I would like D8 or posedion to directly challenge Joomla. Hope, Boonex will listen!!!