So if I default on a loan, I should not pay the collections agency, and after a few months(??) it will just disappear entirely, even off my credit report?
Your statement confused me.
If you default on a loan and it shows on your credit report, either negotiate a PFD (pay for deletion) or wait 7 years (10 years on student loans I think) for it to fall off your credit report.
From a business standpoint, those are your only good options. If you pay a collection agency, but don't negotiate the PFD, you are essentially throwing your money away.