Plus or minus? (BEN MARGOT/ASSOCIATED PRESS)

My motto used to be, like Groucho Marx, that I wouldn’t join any social network that would have me as a member.

This meant that I was largely restricted to MySpace, which kept sending me e-mails suggesting that I try joining a band, “appearing creepier” or “generally behaving more like Tila Tequila” if I wanted to make the cut.

And now Google+ is open to everyone.

Maybe I'm alone in this.

But even as I basked in my Google+ invite, I haven't seen anyone stop using Facebook.

And for Google+ to succeed as competition to Facebook, it needs to — well, compete with Facebook. Right now it's just Another Facebook-Like Service You Can Join, best summed-up in this xkcd comic.

At first, it seemed to be working: 20 million people joined.

But now comes the real Rubicon question: Does joining it mean anything? It’s one thing to double-down on Facebook and Twitter — the two provide meaningfully different services. One offers you 420 characters of inanity from people you met once during your freshman year of college, at an event celebrating the capybara. The other offers you 140 characters of inanity from perfect strangers, and occasionally a quote from the Paris Review about sexual practices best not discussed in a family newspaper.

Google+ was supposed to be a choice, an alternative to Facebook — it served no markedly different purpose, so it would have to compete on its own terms. People seemed open to it. They often complained about Facebook.

But the nature of Facebook was that people always complained and never left. It was like the United States in election season. If you could actually introduce me to anyone who’d moved to Canada because someone he disliked was elected, I’d move to Canada myself.

Then, suddenly, there was somewhere to go. Google+ was calling our bluff. “You said you'd leave, right?” it said, standing on our doorstep with flowers. “You said that once things evolved in a different direction, you'd get out of that unhealthy relationship with that creepy Facebook kid. And, see, here I am, with an intuitive interface and fun animations!”

“I know that's what I said,” we say. “In fact, Facebook recently reminded me of it in that creepy Memories feature, where it suggests random statuses from the past that I ought to be remembering right now.” We sigh. “This is handy — I was wasting a lot of mental space on things like thoughts and memories, and I'm glad that these things are in someone else’s capable hands now. Not that there was any great loss. Most of my past statuses involve enthusiasm about various forms of cheese.”

Leaving aside how creepy this is — forget madeleines, Marcel; Facebook will remind you of all the Things Past that you need to know — Facebook is wise to call our bluff.

“That's it! We're leaving!” we exploded, a scant month or two ago. “Google+ will understand! Google+ respects our privacy, and doesn’t send us targeted ads for Furry Cruises.”

“You want to leave? Go ahead and leave!” Facebook said, grinning smugly, as smugly as you can grin if you are a social networking Web site. “I know you’ll come crawling back, maybe just for one last poke.”

Meanwhile, the roles reversed. Sensing our affinity for bad boys, Google+ left our profiles and the members of our circles visible for the world to see unless we altered the default setting. “This is what Facebook did too,” we murmured.

“I thought you liked it when Facebook did that,” Google says. “You didn’t leave.”

And startled by our momentary absence, Facebook fixed the one area where Google+ was beating it – namely, the default setting that obliged you to share everything with everyone. Now sharing everything with everyone is no longer an obligation — it's more of a lifestyle choice.

And no doubt it will come up with circles soon enough, if we really turn out to be fond of them.

I hate to declare anything dead in the water, even Ophelia, so maybe I'm wrong. Maybe Google+ will develop its own character and find its own niche, separate from the “like Facebook but not Facebook” position it presently occupies.

But social networks always comes back to the party question: Who will be there?

My experience from Google+ so far is that not everyone has arrived. Maybe the opening will change that. But perhaps it won’t.

And if everyone doesn’t migrate, Facebook is waiting.