“I don’t touch Facebook,” declared Michael Romanowicz, 29, a freelance web designer who nixed his profile and more than 300 friends on the social network last year after he decided it was making him unproductive. (Worse, it was showing him too many pictures of his ex-girlfriend.) “I’m a digital professional and I fundamentally disagree with the philosophy of how Facebook has structured their product.”

It’s not that he and the social network didn’t have some great times. “What was really cool was that one of my friends was one of the first few hundred Facebook users, and for some reason he had a super admin access,” he said. They used the account to snoop through strangers’ photos.

But Facebook became “annoying” and “inundating” as it grew, and at some point, it stopped being fun. “So I deleted it. And what I found was that everyone I’ve had a real relationship with, after I deleted the account, sent me an email and was like, hey, how come we’re not friends anymore?” he said. “And I’m like, ‘No, we’re totally still friends! Thanks for sending me an email because that proves that we’re still friends!’”

Last week, Google finally launched its full-on Facebook competitor, Google+, which Wired called a “bet-the-company move,” implying that Google’s future depended on whether Facebook’s 600 million users would take to a new social network. Encouragingly for Google, the corpses of Facebook’s predecessors—often cited as cautionary tales of web consumer fickleness—were also in the headlines: Myspace was bought for a 10th of the $327 million it sold for in 2005 just before it hit 100 million users, and the proto-social network Friendster relaunched with a whimper, as a gaming site that prompts users to sign in to find their friends, with Facebook.

Facebook lost more than six million users in May according to a widely publicized report by InsideFacebook, which collects data on the site. That number was disputed by Facebook and other third-party researchers, who reported a net gain for the month, but everyone’s data show Facebook’s momentum has slowed—and the web’s power users, at least, seem to have moved on. These days, Mr. Romanowicz is more into Instagram, the photo-sharing iPhone app that that launched in October, and GroupMe, the group-texting service that came out in August.

“The tech-savvy crowd has grown tired of Facebook,” Jason Calacanis, dot-com publisher of the bygone Silicon Alley Reporter, wrote this weekend in his email newsletter predicting that Google+ will be a “crushing success.” Mr. Calacanis recently surveyed an audience of techno-hipsters at the Future of Web Apps Conference. The vast majority said they were using new services for things they used to do on Facebook. “I asked how many people were using Facebook more now than last year,” he wrote. “Almost no one raised their hands.”

Mr. Romanowicz’s friend Gordon Cieplak, 27, is co-owner of Handsome Code, a web development shop that carries the slogan “more bicycles, less social networks.” He thought Facebook was “amazing” when it first came out. “I was like, wow, it’s such an incredible user experience and the design is so good,” he said. “I had never seen anything quite like it on the Internet.”

Gradually, the site lost its luster. Facebook is an addictive time sink disguised as a complement to your social life, he explained to The Observer. (People collectively spend 700 billion minutes per month on the site, according to Facebook.) A few weeks ago, he quit in favor of Twitter and Tumblr.

“Among my friends, we all sort of loathe it,” he said. “It’s kind of the same way we loathe cars. They’ve just become part of this, like, legacy infrastructure. Sometimes we use them, but we mostly dislike them.”

Facebook had fewer than 200 million users when Slate’s Farhad Manjoo declared it a universal good in 2009. “It’s time to drop the attitude: There is no longer any good reason to avoid Facebook,” he wrote, accusing non-users of harboring an “affectation” to make a “statement.” “‘I’m not on Facebook’ is the new ‘I don’t even own a TV,’” Rainn Wilson wrote recently on Facebook, a comment 792 people liked.

But Facebook has become the lowest common denominator on the Internet in its effort to conquer the world, and this may be its downfall among a certain class of technophiles—once your grandmother starts poking you, it may be time to find a new hobby.

The Observer asked Mr. Cieplak if he feels cool about not being on Facebook. “To the same degree I feel cool about not living with my parents in my 20s,” he said.

The anti-Facebook cohort cites a range of reasons, philosophical and psychological, for quitting Facebook. “It is a system designed to not make you feel good; it’s designed to make you click more and go deeper into the hole,” said Cody Brown, 23, who co-founded a Web start-up called Nerd Collider. “It can be totally soul-sucking. They also have something like 52 reasons to send you email.”

David Shapiro, a pseudonymous Clinton Hill–based blogger, 22, quit Facebook after about six months on the site. “Facebook is this massive social experiment that is totally untested and could be fucking with people’s self images more than anything in decades,” he said.