Look at a map of ST 'Known Space' - The Federation is nearly as big as all other space-states combined. When it comes to assimilation, humans got the Borg beat.
Why was the Federation even involved in the problems between Bajor and Cardassia? And in the end, both groups were our 'fiends', and possible future UFP members? Getting involved in far-away 'brush-fire wars' so that eventually you'll have another group to add to your side... sounds familiar. The U.S. only fought a 'cold war' with Russia (and possibly China, except we technically didn't even recognize them as a country back then), but the Federation appears to be fighting a cold war on every front, with everyone. The Klingons land on some backwater world to talk to the inhabitants, and Starfleet is beaming down an away team two seconds later. 'Control through kindness' is a real thing. Is it evil? Not exactly... but then, the Borg make the same point; assimilate everyone and there is no more conflict, bigotry, starvation, lack of other resources, etc. Once everyone is 'the same', you have a nice little civilization of well-behaved drones. So whats the difference between programming fed directly into your brain, and being brainwashed by your culture (and insane amount of rules/laws) to think you are living in paradise? Is it paradise, if you don't earn it? Its hollow. Thats the point.
Eddington's point is that in a meta way, Rodenberry's dream doesn't work. its a cultural dead-end. 99% of the advancements made by humans were done because of adversity (conflict, environmental, etc.). Without an opposing force we have stagnation. Good little worker-bees in a hive.