On June 22, Fran Kelly interviewed Scott Morrison on the ABC’s RN Breakfast on several issues, including same-sex marriage. That was Kelly in her role as presenter on the taxpayer-funded public broadcaster.

Last Sunday, Kelly was one of the panellists on ABC television’s Insiders program. She joined the Guardian Australia political editor Lenore Taylor in criticising Malcolm Turnbull’s approach to same-sex marriage. That was Kelly in her perceived role as an advocate.

Clearly Kelly is well qualified to be a presenter or advocate. It’s just that it’s very difficult to perform as an impartial presenter on a Wednesday and as a committed activist on a Sunday. Kelly happens to believe that she can be both, hence her comment to journalist Tim Elliott in March 2012 that she regards herself as “an activist”.

It seems that it was during Mark Scott’s time as ABC managing director that ABC journalists were encouraged to become advocates. The BBC, however, continues to insist on a strict division between these roles. BBC presenter Andrew Neil visited Australia last year in his capacity as chairman of the board of The Spectatormagazine. At the time, there was considerable discussion about whether Scotland should vote to remain within the UK. It was clear that Neil, a Scot, had a clear position on the issue. But he refused to state his personal views in public. His position was that, as a presenter of Sunday Politics on BBC One, he should not participate in the public debate.

Jeremy Paxman, who presented BBC Two’s Newsnight program until 2014, has described himself as a “one-nation Tory”.

The personality, who recently presented the BBC One documentary Paxman in Brussels: Who Really Rules Us? concerning Britain’s relationship with the EU, wrote an article on the EU for Radio Times magazine.

Radio Times was sold by the BBC in 2011. Even so, BBC executives chose to vet Paxman’s article because it coincided with the May release of Paxman in Brussels. The article did not advocate the Brexit cause but the author was critical of the EU and the impact of the EU on Britain.

When a senior BBC executive wanted changes to the Radio Times piece, Paxman withdrew it from publication.

I would have liked to hear Neil’s views on whether Scotland should remain in the UK. And I would have been interested in reading Paxman’s unedited position on Britain and the EU. Yet there is a certain wisdom in BBC management attempting to prevent high-profile presenters from becoming players in the political debate.

Leading ABC presenters such as Tony Jones and Michael Rowland tend to refrain from mixing it in the public debate as commentators, columnists or on Twitter.

However, many do — including Emma Alberici, Phillip Adams, Julia Baird, John Barron and Kelly, plus, on occasion, Leigh Sales.

On June 21, Alberici tweeted a photo of a poster used in the Irish referendum on same-sex marriage featuring a man, a woman and a baby. It declared “Children deserve a mother and a father”.

Alberici commented: “LGBTQ people in Ireland were offended by these posters during the referendum. It’s what LGBTQ families here dread.”

The following day Sales told her followers that Labor frontbencher Penny Wong’s Lionel Murphy lecture was “worth reading”.

This was an effective endorsement of the Labor Senate leader’s support for same-sex marriage and opposition to a plebiscite on the issue. Then, on June 26, Kelly declared on Insiders that “there shouldn’t be a plebiscite”.

In recent days all three ABC presenters have interviewed politicians on same-sex marriage. Sales spoke to the Treasurer, Alberici to Foreign Minister Julie Bishop and Kelly to Bill Shorten. These interviews clearly conflated the role of the journalist as presenter and the journalist as activist.

The ABC is a conservative-free zone without one conservative presenter, producer or editor for any of its prominent television, radio or online outlets.

This is all the more reason it would make sense for the ABC management to insist on a clear divide between presentation and advocacy. Since ABC staff, rather than management, effectively run the public broadcaster no change should be expected.

Many journalists are among the large section of the intelligentsia who believe that their morality is higher and their wisdom greater than that of most of their fellow citizens.

In the wake of the Brexit victory in Britain late last week, the Ten network’s contributing editor Paul Bongiorno raged on Twitter: “Brexit proves every lie, every emotion is exploited by the Right to thwart rational no brainer outcomes. The reason we have a plebiscite (on same sex marriage).”

In other words, to Bongiorno there is only one proper view on the EU and same-sex marriage; namely, his.

Similar views have been pronounced by Fairfax Media’s Mark Kenny. He sermonised last Monday that “the plebiscite is the political hidey hole of the craven” and declared the proposed same-sex marriage plebiscite as “divisive and wholly unnecessary”.

This despite the fact opinion polls suggest a clear majority of Australians want to have the opportunity to vote on the issue. Moreover, Ireland survived a referendum on same-sex marriage and there is no reason to believe Australia is a less tolerant or accepting nation.

The concept of the plebiscite is part of Australia’s democratic tradition. Plebiscites were held in October 1916 and December 1917 on conscription for overseas service during World War I.

In May 1977, Australians were given the chance to express their preference for a national song. The winner became, in time, the national anthem.

If the Turnbull government gets its way, there will be a plebiscite on same-sex marriage.

It’s understandable the proposal that the traditional view of marriage, as a union between man and a woman, should be changed will be contested by advocates on either side of the debate.

But it is not the proper role of journalists to use their privileged position in an attempt to close down debate.