There can now be little doubt that David Cameron and Iain Duncan Smith have failed to produce the welfare reforms they promised when they came into government. An aggressive programme designed to change almost every strand of Britain's social security system falls further into disarray every day.

Universal credit, the work and pensions secretary's flagship reform, has been beset by IT problems, staff criticism and delays since its launch. It is now clear that the project has been "reset", and will not now be rolled out nationally until after 2015. A recent survey of the staff working on the project highlighted "a near-complete absence of anything that looks like strategic leadership in the programme".

The work programme has missed every target set for helping people to find work, and in half the areas that are running the scheme it has proved less successful than doing nothing at all.

The youth contract, Nick Clegg's plan to incentivise businesses to take on young people who'd been out of work for more than six months, using £1 billion of public money and trying to help 160,000 young people into work, saw a take-up of just 4,690 recruits from June 2012 to May 2013. The deputy prime minister admits the plan has failed, blaming the creation of a "hotchpotch of schemes".

Personal independence payments (PIPs) were intended as a replacement for disability living allowance (DLA) – the benefit package that helps 3.2 million seriously disabled people with the costs of their care and mobility needs. Ministers complained that "at present 71% get the disability benefit for life, without any systematic reassessments to see if they still need it".

Apart from the fact that this claim simply wasn't true – there are no lifetime awards for DLA and there were always systematic, face-to-face claims assessments – the government has also admitted defeat on this "reform" and delayed testing the very people it complained were "festering" on benefits until after the 2015 election. Ministers feared an avalanche of news stories about the half a million profoundly disabled people set to lose out under the new benefit just before an election. Yesterday they got a taste of the protests to come, with a lobby of parliament by the pressure group Disabled People Against Cuts. It seems that "festering" is OK if there is a political motivation.

But no welfare reform is failing more damagingly or harming more vulnerable people than the national rollout of employment and support allowance (ESA) and the now infamous Atos work capability assessment.

Work capability assessments were introduced by the last Labour government, but were only at the trial stage when the coalition came into office. It was clear from the trials that the tests were failing – especially those for people with long-term chronic illnesses and mental health conditions. However, the new government decided to roll out this test to 1.6 million of the most vulnerable long-term incapacity benefit claimants, and justified the decision by saying that "in most cases [of ESA and PIP] this will also involve a face-to-face assessment".

Department for Work and Pensions officials claimed that sickness benefits were a "lifelong incubator for idleness", with decisions made only on the information provided on claim forms and from the health professionals who knew the claimant best.

Work and pensions minister Mark Hoban recently confirmed that "we are currently reassessing (with very few exceptions) everyone on incapacity benefit", and the DWP's own information states that for work capability assessments "a trained healthcare professional carries out an initial paper-based assessment. Where evidence exists that a claimant meets the Support Group criteria (including being terminally ill), the healthcare professional can advise the DWP decision maker that a face-to-face assessment is not needed. All other claimants are required by the DWP to undergo a face-to-face assessment."

Campaigners always warned that it was simply impossible to put so many people through a face-to-face assessment. The deadlines were impossible, and such a tight timescale led to more delays and mistakes. Atos have employed extra staff, increasing the assessments they conduct from 25,000 a month to more than 100,000, but it still isn't enough. There remains a backlog of around 500,000 claims, and one testing centre in Leicester complained that the process – which is supposed to take 13 weeks – is taking over 40.

In fact, paper-based assessments make up a staggering proportion of successful claims. Far from pushing everyone through a tougher process, it appears very little has changed, despite government rhetoric that has terrified many sick and disabled people.

It now transpires that 60% of claims reassessed as being made by people unable to carry out any kind of work-related activity were based on the evidence of paperwork alone. Even more surprisingly, 48% of those being placed in the work-related activity group – where claimants may be able to carry out some work in the future (with the right support) – are based on paper-only assessments too. Government rhetoric is revealed as just that: rhetoric, designed to frighten and confuse the most vulnerable. Duncan Smith and Cameron could have made this clear from the start, and alleviated many of the concerns over ESA. But they chose not to.

So far more than 150,000 people have been wrongly assessed as fit for work; 40% of decisions go to appeal, and 16% are found to be legally wrong. As campaigners point out, testing those who will never get better is time-consuming, costly, to the taxpayer and causes untold stress to the most vulnerable sick and disabled. Like so many of this government's welfare "reforms", if ministers had been honest from the outset instead of pandering to the rightwing press, so much fear and suffering could have been avoided.