I go online to be exposed to novel information.
I open up firefox, check my email. Then check my RSS feed. Then check Overclock.net. Maybe in that order, maybe not. I dunno. Maybe I just stare at the screen until I remember something I wanted to look up on Wikipedia. Maybe I go to Netflix and watch FireFly or Star Trek or something. I check my Google+. I check my Youtube subscriptions and maybe watch a music video. Maybe I read something irritating and write a long rant or article. I don't know.
I go on line because that's where I encounter new information and interact with people. That's what everyone does.
Not saying this study is worthless, of course. All knowledge, no matter how abstract or "common-sense" is worthy. But I don't think that "no reason" is really no reason. No reason is really just "I didn't have a specific website in mind." But there is a reason; people wanted to be exposed to novel, unusual, important, or entertaining information. That's why the internet exists as it does today.