Accounting, surprisingly to folks who've never studied it and think it's simple arithmetic, requires judgment, based on rules that are sometimes grey and subjective. When you add in legal complexities, it becomes... well, more complex and therefore open to manipulation.
For instance, Enron was able to hide many liabilities by marking it (in hindsight) below market, since... there was no market for said liabilities. So it was impossible to value them. Furthermore, it hid other debt in obscure subsidiaries that were only tangentially, legally and fiscally speaking, connected to Enron.
The blockchain confirms, with better accuracy than existing systems, "X transaction occurred between Y and Z partners." It does not confirm "X's assets were appropriately valued and marked as such to a non-existent market, and X is most definitely a legal subsidiary and is overseen by the fiduciary duty of A Holdings, Corp."
The blockchain has the potential to be a far more efficient settlement system. But saying it prevents Enron or Madoff is simply not true at all.
The blockchain, rather, represents a better clearinghouse merely by being a decentralized platform to account for payments rather than a centralized one.
OP says this prevents accounting fraud. Not one iota.