I'm not sure if you were insinuating that SE's fragmentation was a bad thing. If you are, SE actively fragment's itself for a reason. Watch Spolsky talk about it here: http://vimeo.com/37309773
Quora's non-fragmentation is it's ultimate downfall.
Im not sure yet if the SE fragmentation is a good thing or bad yet. From one perspective I see where they are coming from and why they are doing it. But in today's age of IT where the specialists is dead and people are more-or-less required to be an expert generalist it is very frustrating to use SE. I find myself more or less giving up when a question gets migrated to a SE Im not a 'member' of yet (they should really just make all users IDs members on all their sites whether people use them or not). Whether you are a webmaster, server admin, programmer, general PC user or just want to ask a general question about how SE works, I shouldn't need to go so many places. It's really 50-50 in my mind if they are doing a good thing or bad (and it probably doesnt matter in the end)
But I have never used Quora, so I know nothing about it beyond getting the blurred webpage when you are not a member there. Ill check out that video now.