Not really. Contrast the cluttered mess that is PoF to OkCupid, which has decent usability and reasonable information architecture. OkC's design is also better at extracting the right information from more users more consistently, meaning the resulting corpus of data is more complete. Which makes for a better product, since it's easier to find the sort of people you'd be into.
PoF is successful in spite of its questionable design, not because of it.
Or an example of the network effect overriding other condsiderations. PoF got big before OKC did, so that's where the people are.
Even with that factor though, I found PoF borderline unusable after a little experimentation and stopped using them in favour of OKC. I can't believe I'm the only one like that, or that there aren't some who simply dropped off PoF into nothing.
If that crappy site can extract value at such a high level, I'm sure a few reasonably small tweaks could extract significantly more.
At the scale pof operates at you have to A/B test everything because some things are very counter-intuitive.
My favorite anecdote of his (tried to find it on his blog but google is failing me) was when he briefly fixed the problem I hated most about the site: the aspect ratio of the profile pic thumbnails being off.
What happened is that it cost him lots of money. And the explanation as to why makes sense too: when the aspect ratio is messed up people can't tell at a glance what the person looks like so they click through to people's profiles a lot more instead of just scanning the top bar/search page. When your business model is based on page impressions getting people to load more pages means you get more money.
So in that case at least it's better for his pocket to have something that's obviously broken (and easy to fix) on the site.
If your business model is dependent on being just awkward enough to use that you generate extra page impressions but not awkward enough that you drive away traffic, to borrow an aviation term you're flying awfully close to coffin corner. Particularly when you're dependent on network effects; if enough people start discovering something that's less awkward for them (such as OKC), the network effect will start working against you and you're suddenly so 2004 with a database of inactive users and a reputation for being awkward to use. Plus, if you're dependenet on awkward usability inherently generating more pageviews, surely by definition those pageviews are also more rapid so the time each ad is being displayed to each user is lower, so the savvy ad buyer would also be paying less.
Now, I could make the case that PoF has ridden the wave for long enough to build Markus enough money that if it all fails tomorrow he's still made for life and only really lost pride, but....
Take all this with a grain of salt, as I'm about to get vague and handwave-y. According to some article I read [citation needed], the fact that their interface is crap actually drives more pageviews. E.g., that profile pictures are distorted is searches actually encourages people to click through to profiles to see better-looking photos.
So poor usability actually is a feature.
Which comes back to the old argument about advertising-driven revenue models resulting in poor user experiences, since the "user" from a revenue model is the advertiser and YOU'RE the product.
too bad both sites use the old stereotypical pictures+profiles approach to dating unlike flirtrs which actually makes you go meet people (cause you know, if you are trying to meet people it helps to go meet them)
PoF is successful in spite of its questionable design, not because of it.