It was the Duke of Wellington who originated the defiant statement, “publish and be damned!”, in response to being threatened with an unflattering portrayal in a courtesan’s memoirs. In subsequent years, the exclamation became associated with hard-nosed newspaper editors determined to run juicy stories if they saw fit. In the age of social media, the notion has become more complex; not so much because there is any shortage of critics lining up to damn Facebook, Twitter et al, but because of the ongoing debate about who or what is a publisher.

Around the world, Facebook has close to 2 billion users. Twitter use may be in decline but 300m tweets a day is not to be sniffed at. The number of images posted on Instagram is, conversely, on the rise, while some estimates suggest that 5bn videos are watched daily on YouTube. And if someone tells you a recently discovered fact, they’re likely to tell you they “found it on Google”.

As a consequence of the internet revolution, more material is now published than ever before. And yet never has it seemed so unfashionable to admit to being a publisher. Google remains simply a search engine, helpfully directing internet users to a choice of destinations. As for Facebook and its ilk, they are merely “platforms”, enabling even the most illiterate and deluded among us to serve up our vital thoughts to the rest of mankind.

The optimism that underpinned the development of social media sites was itself buttressed by the kind of sunny, Californian libertarianism which perceived the internet as an equalising force between rich and poor, strong and weak, oppressed and free. The only trouble, as it turned out, was that baddies turned out to be equally adept at using the internet as goodies. Twitter trolls are now ten a penny, while terrorists, child abusers, and bullies of every description have used mainstream websites for nefarious means. Even free and fair elections are, allegedly, at the mercy of wonks who know a thing or two about analytics.

Jeremy Corbyn ambushes Theresa May during Facebook Live event with TV debate challenge

In the last year, criticism of the internet’s big beasts has steadily grown. In March, executives from Twitter, Google and Facebook appeared before the Commons’ Home Affairs Select Committee. Their answers about the regulation or removal of inappropriate content were not, said committee chairwoman Yvette Cooper, “particularly convincing”. A month on, and Facebook came under renewed pressure when Steve Stephens posted footage of himself shooting dead a random stranger in the US.

For years, platform providers have been ready beneficiaries of the legal principle that they cannot be held responsible for material posted by users. The most they had to be concerned about was having in place mechanisms by which inappropriate content could be flagged, and if need be removed. And on the face it that theory is sound: a telephone company isn’t responsible for the actions of a heavy breather; an online news site is not, unless it pre-moderates, liable in the first instance for a defamatory remark made “below the line”.

Yet increasingly it is hard to maintain the distinction. For one thing, so much grossly inappropriate material is posted on social media that post-hoc action seems inadequate. The potential for posting live content – especially videos – makes after-the-event moderation feel close to redundant. What’s more, algorithms actively favour some material at the expense of other content. And of course advertisements are sold on the back of, and in order to monetise, all sorts of things, from news reports and blogs to videos and picture galleries.

Facebook’s own statements are indicative of its discomfort, pulled between libertarian ideals and the need to show that it doesn’t forego its social responsibilities in the pursuit of annual profits to the tune of $1.5bn. Monika Bickert, the firm’s head of global policy management, has argued that “no matter where you draw the line, there are always going to be some grey areas”. Facebook, she told the Guardian, “is a new kind of company. It’s not a traditional media company. We build technology and we feel responsible for how it’s used. We don’t write the news that people read on the platform”.

Facebook's brand new office in Singapore Show all 10 1 /10 Facebook's brand new office in Singapore Facebook's brand new office in Singapore A mural from local artist Justin Lee CK blending East and West. Facebook Facebook's brand new office in Singapore Visitors can leave a message on the 'Write-Something-Wall' Facebook Facebook's brand new office in Singapore Sign in here Facebook Facebook's brand new office in Singapore The library space Facebook Facebook's brand new office in Singapore Teach gear vending machine where employees can tap their tags and get what they need in case they forgot to bring their equipment at the office. Facebook Facebook's brand new office in Singapore An internal staircase, adorned with acrylic confetti by Singapore designer Dawn Ng, connects the four floors comprising the Singapore HQ Facebook Facebook's brand new office in Singapore Relax at the game corner Facebook Facebook's brand new office in Singapore The hangout area, use your break to try the Instagram Anti gravity booth or the Facebook mahjong Facebook Facebook's brand new office in Singapore The Instagram "gravity booth" that Facebook set at the hangout area for the athletes at the Southeast Asian Games that was held in 2015. The booth's furniture is set at a 90-degree angle rotated left, turn the picture to the right and it will look like you are floating. Facebook Facebook's brand new office in Singapore Drink in the beer garden anyone ?

“Traditional” media, of course, has skin in the game. Facebook and Google are cannibalising others’ journalistic content, making money from it at no risk to themselves, and doing little to help internet users distinguish between real news and the fake variety. All of that hits “old” media in the pocket.

Yet this is not some establishment conspiracy to silence social media or bring down the internet’s big corporate winners. The simple truth is that Facebook already uses software to block some content from being uploaded by users. It doesn’t have to be a “traditional media company” to recognise that this is effectively an editorial decision of the kind made by publishers of various stripes for decades.