I don't think it's significantly different with being subscribed to numerous listservs. We tell ourselves that we really don't have to read the mail that often we spend more time filing that reading, but making the big leap and actually stopping our subscription? Isn't that being a bit drastic?
In my particular case it was less a question of getting more "free" time, than of "freeing" myself from the bondage of feeling compelled to continue reading postings that didn't really interest me that much. Somehow we've made such a big thing around "online community" that I'd begun to feel that it was my responsibility to continue subscribing. How could I let all those other subscribers, people whom I didn't know at all, and probably had close to nothing in common with, down. And of course the longer you continue to subscribe the harder it becomes to make the big leap and halt the subscription.