Do deliver and they don't get paid because the buyer purchased with money that doesn't exist.
Lose-lose situation!
What we got in 2008 was central banks (eg Fed and ECB) willfully collapsing nominal GDP in their economies. Have a look at the dot-com bust or Black Monday for comparison.
What on earth are you talking about?
The credit risk was a very real problem; Kaupthing, Anglo Irish, RBS, Lehman etc.
In 2008 they didn't. Instead they actively tightened monetary policy by eg introducing interest on excess reserves. The ECB even hiked interest rates.
Companies defaulting on debt doesn't need to bring down the economy.
For the US, you can also see how the construction sector had been winding down for years (eg as measured in construction employment) without an impact on overall unemployment. The crisis was entirely avoidable.
See https://www.cato-unbound.org/2009/09/14/scott-sumner/real-pr... for a bit more background.