On the second day of the new year, I awoke to the news that a man had been assaulted on 42nd Street and Eighth Avenue, and there had been a fist fight on the east side of Central Park. The previous day, the morning update featured an overnight fight at a Burger King in Hell’s Kitchen, possibly involving an ice pick, and an assault involving a knife 10 blocks south of my apartment. In both cases the news, which was reported to some 4,000 people in the vicinity with the Citizen app on their phones, was prefaced with demands from the app to turn on push notifications and the entreaty, “Keep your loved ones safe with urgent crime and safety alerts near them in New York.”

Citizen, which was launched in 2017, is a glorified police scanner that promises to help users “stay safe and informed”. It invites input from witnesses – mostly involving shaky phone footage of police milling around while a stretcher is carted by in the background – and, bafflingly, includes a comments section, in which users speculate fatuously on the crime in question and quibble over the accuracy of the map function. It is grimly fascinating, mildly addictive and, relative to its stated aims, totally without value.

It is also part of what feels like the continuum of online feeds that, from Facebook down, promise to improve community while actually playing on people’s worst rubbernecking instincts to broadly divisive effect.

There’s no question that Citizen can be entertaining. Who can forget the alert from several months ago informing the concerned citizenry of New York that a man with no pants on was wandering around the corner of 34th Street and Fifth Avenue? Engagement seems to be increasing. Last year, CNN reported that a car crash in Brooklyn garnered more than 130,000 views, 600 comments, and seven separate videos, while news of a recent cab on fire in Times Square was related to 31,000 people via their phones.

What one is supposed to do with this information remains a mystery. There is no real public interest defense of the app, which feels like a heightened version of all other entertainment feeds designed to spike your adrenaline, make you angry or scared, or otherwise provoke useless and directionless emotion. It’s feasible that, when reports of a man throwing chairs around inside a Taco Bell in Midtown come through, you might alter your lunch plans, but the broader appeal – that this raw information culled from 911 is actionable intelligence – is nonsense.

Recreationally, it feels akin to checking the sex offender register in one’s neighbourhood – which I did a few years ago and discovered, inevitably, several convicted rapists, including one living two streets away who had a history of distributing child porn. A blurry photo of the guy was attached. What, exactly, was the point, other than to give myself a horror-movie chill?

A few months ago, scores of police cars converged on a street several blocks from me, and Citizen said there had been a shooting. There was no context and no further intelligence, so while the news was briefly thrilling, it did to the word “information” what has already been done to the word “engagement” – emptying it out to the extent practically of reversing its meaning.

• Emma Brockes is a Guardian columnist