As a counterpoint: I have. I've also used conferences as a means of getting face-time with people I otherwise only interact with online. There are also people I share information with, but only interact with once a year at a conference (that is, the conference is the means of staying in touch). Sometimes its also about meeting people who, while you might not stay in touch with them, if for some reason you end up interacting with them in the future, they remember you and you have a head start (last year I almost got a job (I turned it down only because it would have increased my commute beyond what I was willing and I wasn't prepared to relocate) because I met the CTO at a conference 5 years ago). The value of these things varies, of course, so I won't say that conferences are definitely and always worthwhile, but they definitely can be.