I don't think on-line dating is a sham. It seems to be a natural answer to the growing problem - meeting people in general, and potential romantic partners in particular, gets an order of magnitude harder when you finish education. For most people, it's suddenly 9-10h/day spent at work (8h + commute), and it's hard to maintain a social life when you're both a) tired every evening, and b) required to be in good shape the next morning. Of course, many deal with it perfectly fine. Many deal only sort-of, which is why workplace romance is so common even though employers try to fight it as much as possible. But then there's a large group that simply can't find the right opportunities. On-line dating is great for those. And it works at least sometimes - I personally know of people who met and got married through one site.
That said, I'm totally not surprised by your observation about Facebook events. It's more natural to meet people like that, without prior obligations. People tend to be more open, and conversations more genuine. Especially if this is a topical event, you automatically have people pre-selected for interest compatibility. Just like money can be detrimental to the projects of passion, on-line dating seems like "trying too hard", compared to casual meetup. I tried using a dating service once, and such dates actually felt to me more like a business transaction than a meeting of strangers. But then again, I'm shy, I prefer going the roundabout way :).
And to add N=1 story, my success in finding a potential future friend or romantic partner tends to be inversely proportional to how much I try, and a direct function of number of events and public appearances I make. I'm thankful for services like Facebook and Meetup, which let you know about interesting events in the area without having you spend a ton of time on finding them.