The political chattering class owes the people of Australian an apology. Nearly all of us, to a woman, were badly off-beam about the transformation of Australian politics last September.

We too were overcome with a sense of relief that the chaos and debacle of the Abbott era was over. Not that it didn’t give us a constant stream of copy. Nothing to write? Just wait five minutes and an Abbott minister, usually a senior one, would stuff up, or Abbott would say something outrageously dumb in front of 40 flags that topped his previous efforts, or there’d be a leak.

But beneath it all, there was a terrible sinking feeling that this was bad for the country, that we couldn’t continue like this.

Enter Malcolm Turnbull. Turnbull the adult, Turnbull the brilliant communicator, a changed Turnbull who had learnt his lessons from 2009 and would now lead a rational, mature, consultative government. He promised to give us a genuinely Liberal government, in contrast to the reactionary rabble he had just ousted, and he promised reform via an intelligent conversation with the electorate. The years of destructive, negative politics from Abbott, the years of internecine squabbling from Labor, were at long last over.

For a while it seemed to work. Turnbull was charming and, yes, Prime Ministerial. He refused to rule out reform options, insisting he was going to change politics by refusing to play those sort of petty games. He brought Martin Parkinson back to run PM&C and put his former departmental secretary into the role of chief of staff. A productive partnership between the public service and the government, rather than the attitude of unbridled loathing and oppression which existed under Abbott, seemed possible.

Then it went wrong. Turnbull’s government is adrift, there’s open warfare within it, and the only decent policy on tax is coming from Labor. It now appears the much-vaunted tax reform package will be barely worth the term “minimalist”, with almost every worthwhile tax reform now ruled out because of backbench pressure, the desire to run an uncluttered scare campaign or, most bizarrely of all, because — according to the Financial Review — superannuation is too complex. We’re not even going to get the relatively small but worthwhile efficiency gains of removing the current, dumb exemptions to the GST.

What we missed in the relief rally that accompanied Turnbull’s ascension was that merely because there was a new prime minister, that didn’t mean the underlying causes that drove Australian politics into the ground in the first place had vanished. They were still there, and still capable of damaging politics and policy.

Thus, Labor, which had suffered at the hands of Tony Abbott’s relentless negativity, was never going to give Turnbull and his statesmanlike call for mature debate a free pass. It mounted a scare campaign on the GST, one that never reached Abbottesque proportions — no cities were going to be wiped out, there were no python strikes and cobra squeezes (or was it the other way around) — but enough to so rattle the Coalition backbench that the government came under serious pressure to leave the GST alone. However, Labor partly made up for its sins by doing something Abbott never did — putting forward sensible, coherent but politically risky reform proposals itself.

But the Abbott approach to policy lingers on the Coalition backbench. That approach was characterised by politics first, help for favoured sectors next, and good policy — including dealing with the budget deficit — only after those options had been exhausted. There’s a clear aversion to any significant tax reform on the backbench, and no interest in addressing the fiscal challenge of getting the budget back to surplus — only in what tax cuts can be waved at voters to secure an election win. This was neatly symbolised by Tony Abbott this week standing up in the joint party room and, with a straight face, demanding the government cut spending and cut taxes. Under Abbott, taxes rose from 21.5% of GDP under Labor to 22.3% when he was ousted, and spending rose by a whopping 1.8 percentage points of GDP to 25.9% of GDP.

Indeed, incoming Treasurer Scott Morrison revealed spending had actually reached 26.2% of GDP in the early months of this financial year. Shorter Abbott: do as I say, not as I did.

But Abbott was always entirely uninterested in consistency, or logic, or evidence — the po-mo prime minister whose casual approach to the facts made him a dab hand at tearing things down but entirely incapable of doing the job of prime minister, which involves leading and building.

That aversion to reality in favour of whatever is convenient at the time wasn’t confined to Abbott. It infected his colleagues, indeed the entire party. It’s why Joe Hockey proved even worse as treasurer than many had expected. But it has also affected Scott Morrison, a man who has only been in politics since 2007 and whose shadow ministerial and ministerial experiences were almost entirely under Abbott. Yesterday’s debacle over the BIS Shrapnel report was beyond any gaffe Joe Hockey ever made as treasurer, and comes not long after a performance at key policy set-piece at the National Press Club that caused even the government’s media allies to savage him.

Morrison is yet to demonstrate any capacity to fulfill the basic political role of Treasurer — effectively arguing the government’s economic narrative and destroying the opposition’s economic narrative. But then, given his political experience, why would he have that capacity? His time as immigration minister was devoted to preventing any scrutiny of the government’s asylum seeker policies through the spurious invocation of national security, and in any event Labor was in hiding in that portfolio (and has one of its worst-performing shadow ministers, Richard Marles, in the portfolio). When Morrison was exposed to scrutiny, such as when Reza Barati was murdered, he bungled badly (who can forget Morrison insisting Barati had caused his own death by escaping?).

Like Abbott and Hockey, Morrison has never had to develop the skill of coherently arguing for a positive policy. Now that he needs to do it, he can’t.

That Abbott remains on the backbench emboldens Turnbull’s opponents, and he himself is clearly embarked on a campaign to destroy the man who replaced him. But even if Abbott had left politics after his ouster, the toxic legacy of his approach as Liberal leader remains and will continue to undermine the capacity of this government to govern rationally. At least while the Gillard government descended into a self-indulgent rabble it continued to produce policies like Gonski, health funding reform and an effective emissions trading scheme. This government has all the policy-aversion of Abbott and now has its own version of the Rudd-Gillard disaster.