When he was communications minister in the Howard years, Richard Alston accused Labor of having a “mogul-centric media policy”. Rarely has a blacker pot criticised a kettle: media policy in Australia under Labor and Coalition governments has been mogul-centric for the best part of 100 years.

In recent decades, free-to-air television owners have dictated policy because of their control over what images voters see during election campaigns.

More latterly still as the media industry has collapsed, News Corp — which could make no headway against the free-to-air oligopolists in the 1990s and 2000s — has been able to dictate the government’s policy towards Facebook and Google and the cowing and destruction of the ABC.

Now half a million Australians very definitely want another kind of mogul-centric media policy: a royal commission into the malignant influence of News Corp. There’s even a degree of bipartisanship in this. The petition was organised by former prime minister Kevin Rudd and supported by another former PM Malcolm Turnbull, whose takedown of News Corp bloviator-at-large Paul Kelly on the ABC earlier this week was one of the most brutal demolition jobs since the days of Spycatcher.

A royal commission into News Corp — which would bring its executives and politicians into the witness box, under oath, with no chance of taking questions on notice, no chance of spinning or lying without consequence — would make for superb theatre.

The extent of collaboration and liaison between journalists, executives, MPs and staffers, especially but not only on the Coalition side, would provide a fascinating insight into how power is wielded in Australia.

Perhaps on that basis alone it would be worthwhile. But it’s unnecessary for identifying the problems that News Corp pose. And it addresses only a symptom of a larger problem that Australia’s media industry, more than ever, is predisposed to the dominance of large oligopolists.

While News Corp is deeply poisonous to civil discourse, is blatantly partisan and has been a key factor in retarding meaningful climate action not merely here but in other countries such as the United States, who has confidence that if it vanished overnight Australia’s media landscape would be problem free?

The Nine media company, with its free-to-air television licences, is chaired by a Liberal elder and former Howard government treasurer, run by a Liberal fundraiser, and has a former Liberal staffer in a senior editorial position. The Seven network is owned by a Liberal-aligned billionaire, Kerry Stokes, and has shifted ever right as its advertising revenues have collapsed.

And as that fate has also overtaken the rest of the media, the entire industry has shrunk, meaning the incumbent oligopolists, even as they shutter mastheads and slash journalism numbers, become ever more dominant in an ever less diverse industry.

Any “solution” to the problem of News Corp runs the risk of simply paving the way for another dominant media company with a toxic ideology and partisanship.

But the solution to this dominance contains within it the seeds for other problems.

If a government legislated the forced divestment of media assets by the largest companies — say, forced News Corp to divest its metro tabloids or Foxtel, broke up Nine so that the Fairfax papers were once again separate, or made Kerry Stokes give up The West Australian — the media sector would complain that it would be uneconomic to operate without the economies of scale provided by their combined operations.

Moreover, it would split off the media operations of the divested assets from key sources of revenue — such as Domain, realestate.com.au — that provided the bulk of profit.

Divestment could thus only occur if the government provided significantly greater financial support for public interest journalism for the divested entities. Otherwise breaking up an oligopolistic industry would more likely destroy much of the industry it was designed to save.

If the nation wants a genuinely diverse media, in which eight or 10 companies control free-to-air and subscription television, major websites, radio and legacy media rather than three or four oligopolists, it will have to pay for it, because it’s unlikely there’s anywhere near enough revenue to support that kind of media.

In fact it’s unlikely there’s enough revenue to support the incumbents.

News Corp has poisoned the well of public life in Australia. Purifying it will be a complicated and lengthy task.