Heh heh... I rub my hands with glee ... looks like we're due for another iteration of the semiannual debate on Nairaland. I'm not yet tired of it, so let me add my two kobo:
First, Nairaland is fundamentally about its content. As far as I can tell, the user interaction is relatively straightforward with very little cognitive dissonance (i.e. your mind stays on the task of communicating, not lost on the mechanics of the interface). You can see/create topics, add your voice, mention and be mentioned, be moderated/banned etc. The website could be all black on white, like 1993-era websites for all users care... it's the content they came for, and for that interaction to be as friction-free as possible.
Second, a simple, uncluttered interface (now I'm talking UX) means things are blazingly fast, even over slower connections or older computers/phones. With nearly 2 million members and over 4 million topics, every millisecond counts. Rather than spend the time on server-side tricks or client-side visual sugar, the site is optimized to grab data, exchange with user, and on to the next request.
Yes, there may be some content caching at the network edges, but ultimately, part of your request will hit the hosting server (if you're logged in), pictures need to be pulled from someplace. Every extra millisecond of computation will ultimately mean more computing power - which can extrapolate into more server resources/more staff/more effort.
Third, a lot of the churn in UI/UX (and even in software in general) is entirely gratuitous, with little or no thought given to actually solving the problem of communication. The only thing I'd like to add is a way to create topics that only a certain subset can view (invite only) to facilitate private conversations. I suppose there's PM, and taking things to WhatsApp, but a group chat on Nairaland could be nice.
But I am curious, what are the unanswered questions?