Don't shoot the messenger is usually a good rule to live by. But it is hard when it comes to Bernie Madoff, the former billionaire serving a 150-year jail term for running history's biggest Ponzi scheme.

Yet, in recent jailhouse interviews, Madoff has given a valuable insight into causes of the Great Recession, whose awful impact has blighted millions of lives across America and around the world. No one can deny Madoff's activities were an appalling fraud, but, he insists, what about the involvement of everyone else in the global financial system.

The HSBC banking group is among those being sued by the victims of Bernard Madoff. Photograph: David Karp/AP

"They had to know," Madoff told the New York Times, referring to the banks and hedge funds that greedily reaped millions in fees from his operations. He pointed out to New York magazine that he refused to give the banks any information as to how he got such high returns and would not let them do due diligence. Yet they never complained.

"These banks and these funds had to know there were problems," he said.

Irving Picard, the bankruptcy trustee in the Bernard Madoff case, in Manhattan. Photograph: Brendan Mcdermid/Reuters

No wonder that Irving Picard, the trustee representing Madoff's victims, has filed a civil suit seeking damages from banks who did business with Madoff. They include big Wall Street names like HSBC, Citigroup, JP Morgan and Merrill Lynch. Just because Madoff is a crook sitting in jail does not mean he isn't right when he tells us to look elsewhere, too.

Yet, unfortunately, Madoff is the only one behind bars.

That is the worst thing about the whole sorry saga. Madoff and his scheme have become a useful foil for the entire finance industry – and a distraction from its venality. It's always Madoff that the tabloids put on the front pages. It's Madoff who is the ultimate banking bogey man. It's Madoff who spurs public outrage and whose jailing has satiated a quest for justice. It is the classic "one bad apple" defence of the kind banks and Wall Street specialise in. It is not the system's or the bosses' fault, they say, it is just a few rogue operators and they have been dealt with.

But we should not be fooled. We should listen to Madoff when he fingers the whole financial sector and the giant firms within it as part of the problem, too. He told New York magazine:

"It's unbelievable … no one has has any criminal convictions. The whole new regulatory reform is a joke."

He's not alone in being amazed that, despite the astonishing frauds and manipulations by Wall Street during the boom years, not one top banking or hedge fund executive sits in jail. It is indeed jaw-dropping.

On Sunday night at the Oscars, film director Charles Ferguson collected, with producer Audrey Marrs, a best documentary gong for his film Inside Job and reminded a watching world of the situation.

"I must start by pointing out that three years after our horrific financial crisis caused by financial fraud, not a single financial executive has gone to jail. And that's wrong."

The cause has also been taken up by Rolling Stone journalist Matt Taibbi. In his most recent piece for the magazine – headlined, reasonably enough, "Why isn't Wall Street in jail?" – he combines an understandable outrage with a forensic look at how the regulators and Wall Street combine to get the financiers off the hook. He scoffs at the fines paid out by banks and executive, rightly pointing out that to the richest people in the world even multimillion dollar payouts are hardly punishment.

What they need, he says, is what Madoff got: hard time; decades of it and in a proper prison. Or, as one congressional aide told Taibbi, "You put (Goldman Sachs boss) Lloyd Blankfein in pound-me-in-the-ass prison for one six-month term, and all this bullshit would stop, all over Wall Street. That's all it would take. Just once."

But there is little sign of that. Madoff seems destined to be a classic scapegoat, held up as proof that action was taken and the guilty punished. Madoff's greatest sin was was not the tens of billions he lost, or the clients' lives he ruined; it was that being caught and jailed allowed the rest of the banking world to walk away from the scene of a much bigger crime.