Surely the days of the Facebook phenomenon are numbered. Imperceptibly, there has been a shift in the zeitgeist and it’s no longer considered cool to share photographs and silly videos, do endless quizzes, promote favourite movies, books and music and send cute little icons to your friends as gifts.

There were two more nails in its coffin this summer. A water fight in Hyde Park, central London, which was advertised on Facebook, degenerated into a scrum at which nine people were arrested and a girl was punched off her feet. And in the High Court, a British businessman called Matthew Firsht was awarded £22,000 in libel and breach of privacy damages after a former schoolmate created a false profile of him on Facebook.

Grant Raphael – who had fallen out with Firsht some years earlier – had posted false information about the businessman’s sexuality, religion and political views. On top of that, he had created a group page entitled “Has Matthew Firsht lied to you?”.

Pretty nasty stuff – but probably not that uncommon. A few months ago I, too, discovered that my identity had been stolen on Facebook. Someone had taken my name, posted a black and white photograph of a girl’s bare feet in the sand and started asking my old school and university friends to become her online “friend”.

Now, I am in no way a Facebook addict (or, as Firsht’s lawyer described Raphael, a “Facebook enthusiast”). When a friend of my husband’s younger sister sent me an e-mail inviting me to join last year, I agreed only out of curiosity and a weak sense that perhaps I ought to because everyone else was.

So I created a skeleton profile of myself. That is to say, I put my name up there, and that was it. I did not join any groups or networks (people in the same city or with the same hobby, interests or pet hates – the list of possibilities is almost endless). However, after a couple of months of passive participation, I decided that perhaps I was being a bit of a spoilsport. The picture I eventually posted showed my baby son pulling my hair – chosen precisely because my face is contorted almost beyond recognition and my son is no longer a small baby.

When I was asked by a friend to post more pictures of my son, I found that I just didn’t want to. I didn’t like the idea of potentially exposing him to a stranger’s eyes. I knew that when I looked at photographs posted by former colleagues, I felt a little voyeuristic. These people, I imagined, would not have been showing me images of themselves in drunken or amorous mode if we still worked in the same office.

Facebook, I soon realised, is a kind of online scrapbook for those who like – or pretend to like – collecting and sharing daily details; at its best, it’s really just a platform for digital drivel.

However, at its worst, Facebook is a cynical publicity and marketing tool. It’s a playground popularity contest in which people cultivate “trophy” friends in their pursuit of micro-celebrity.

And some of them, at least, are not who they say they are. The day after I found out that my identity had been stolen, I informed the Facebook site managers and, within hours, they had removed what they called “the offending content” – which made me think that this was not an unusual occurrence. The Kate Alvarez impersonator vanished from the ether as if she (or he) had never existed.

However, I’d had enough time to see whom she had contacted in my name – 36 people, all of whom were former school and university friends.

A few of them have subsequently been in touch to say that they were vaguely offended or bemused by my monosyllabic responses or lack of any response when they contacted me (or, rather, my impersonator). Aside from that, I have no sense of what damage, if any, has been done.

What remains confounding is what this person imagined she would achieve by such a stunt.

Perhaps she hoped to find out a few personal facts about me from my friends. Perhaps she was after someone I knew rather than me. Maybe it was just an idle prank; maybe she wished she were me; maybe she wanted to spook me.

I will never know. And, unlike Firsht, I would be hard pressed to sue for libel – even if I knew who my impersonator was.

In any case, I have never been comfortable with this hall of mirrors, where you can’t tell whether anyone is who they say they are and everyone is chasing their 15 pixels of fame.

All Facebook ever was, as one blogger says, was “a place to see and be seen . . . show everyone how cool you are and basically stalk other people”.