While the pageload speed may be faster the total speed to find what I'm looking for is drastically slower due to the fact that the interface sucks.

Which paradoxically, seems to be an advantage, because it puts people in a feedback loop where they stay on the site, and every new search provides a tiny bit of reinforcement that builds the habit.

Failing to find what you're looking for because of a frustrating UI is not positive reinforcement. People stay on the site because it is the largest marketplace and they have no alternatives.

That's weird, I've never had any trouble finding what I was looking for on Craigslist. There definitely are ways that they could improve the search interface, but the current implementation works fine for me, and given their user base it works well enough for a lot of people.

It's actually much more variable reinforcement - of course, the most addictive kind.

Each individual search has a low probability of success, but occasionally you'll succeed.