Suddenly, reality TV, where he made his mark, has become reality politics – a seamless colonisation of reality by illusion.

And just in case you think the Trump era may be an aberration, then think again, as speculation swirls around Oprah Winfrey and a possible tilt for the White House in 2020 under the Democrat banner.

It wasn't just her Golden Globe speech this month that set the gossip going. A recent Quinnipiac poll question in the United States, well before her speech, found that almost one-third of self-identified Democrats hoped she ran in 2020. (And if the White House can become an extended reality TV show, what's to stop it changing format to a chat show?)

But Oprah isn't the only celebrity being talked of as a possible contender. Facebook's founder and chief executive, Mark Zuckerberg, is increasingly seen as someone with political ambitions, having transformed himself from a hoodie-wearing geek who mumbled into a smartly suited, power-speaking orator. Commentators note he has hired several senior advisers to former president Barack Obama, including pollster Joel Berenson, strategist David Plouffe and vice-president Joe Biden's former chief of staff and media secretary, Amy Dudley, to work with his philanthropic project, the Chan Zuckerberg Initiative. He has also hired Michael Sheehan, the voice coach who helped Obama in his early days campaigning for the Democratic nomination.

Zuckerberg gave the prestigious commencement address at Harvard in 2016 while also arranging a clause to be inserted into Facebook's governance protocols that enabled him to take a leave of absence, should he desire to work in government, while still retaining voting control over the giant company's board. Last year, he travelled the US speaking circuit, a journey captured on film by photographer Charles Ommanney, who chronicled Obama's first election campaign. He also publicly renounced his former atheism. Such manoeuvrings prompted the London weekly, New Statesman, to ask why he would want to leave the most powerful job in the world to become president of the US?

Celebrity politicians are, of course, not new. There was two-term president Ronald Reagan, who, to be fair, had some political mileage under his belt by the time he entered the White House in 1981, having already served as governor of California as well as an activist within the Republican Party. And there was another Californian governor, Arnold Schwarzenegger.

In the Philippines, voters turned to movie star Joseph Estrada, who was elected president in 1998 only to be forced from office three years later, proving both corrupt and incompetent as president in what was clearly not his best role.

Just why celebrities and politics are coming together is a complex question. One of many explanations is that the traditional representative democracies that started to arise in the late 19th century in the developed world are once again being seen as inept. This has happened before: floundering parliamentary regimes, notably in Germany and Italy, fell to fascism when people who had served in the war saw how effective authoritarian leadership could be in comparison.

And in the 1930s, as the Great Depression spread its misery, there emerged, albeit briefly, a technocratic movement that advocated for decision-making to pass to engineers and economists rather than democratic amateurs. Indeed, strains of technocracy still remain. As late as the early 1990s, distinguished American public policy expert Professor Frank Fischer, of Rutgers University, proclaimed that democracy was "simply incompatible with the realities of a complex post-industrial society".

But why celebrities?

That old Hollywood actor, Reagan, before he ever held elected office, noted as far back as 1966 that his former career shared much in common with his new one, observing: "Politics is just like show business. You begin with a hell of an opening, you coast for a while, and you end with a hell of a closing." In other words, keep the folks entertained.

The ideological gap that once separated major political parties in Western liberal democracies has narrowed in a protracted convergence that has been apparent since the 1980s. This shift has been accompanied by a growing focus on personality over issues and performance over policy. Political parties themselves have become little more than fund-raising bodies and marketing organisations. Slogans have replaced policy arguments.

There can be little doubt that the process of celebritisation has been facilitated by shifts in the media representation of politics, with communications scholars observing that the media – especially television and more recently the internet – constitute a new "public sphere" of discussion. Part of this shift has seen an increasing personalisation of political reporting, with a focus on individual politicians rather than parties or ideological positions. The use of sporting metaphors in reporting politics tends to further the perception that politics is just another game, another form of entertainment vying for your attention.

A perceptive study in 2002 by two American academics, Darrell M. West and John Orman, argued that while the rise of celebrity politics might "reinvigorate a political process that often stagnates", the process has seen traditional political skills, such as bargaining and compromise, replaced by those of media management, slick marketing and fund-raising.

Ultimately, they conclude, serious political issues, which affect everyone's lives, become trivialised "in the attempt to elevate celebrities to philosopher-celebrities".

Even the very notion of celebrity has undergone a change over the years, morphing from an aura surrounding achievement to image alone, a shift neatly captured by the late Malcolm Muggeridge in his book, Muggeridge Through The Microphone (1967), in which he wrote: "In the past, if someone was famous or notorious, it was for something – as a writer or an actor or a criminal; for some talent or distinction or abomination. Today, one is famous for being famous."

Dr Norman Abjorensen, a visiting fellow at the Australian National University's Crawford school of public policy, is writing a history of democracy.