The theoritical benefit of securitization is to sell the exact type of risk to whoever wants that risk.
For example - say you take part in a peer to peer lending market and give a loan to 100 people. You go through a life changing event (e.g. have a kid) and suddenly want to reduce the risk of lending to 100 people over the internet and prefer to put it in government bonds. What do you do now?
You can resell your loans to another party who will take on the risk and the resulting coupon payments from those 100 borrowers. That is in simplistic terms the process of securitization.
However- this process became badly mauled in the 2004 to 2008 period when rating agencies (S&P, Moody's etc) didn't do a good enough job of rating the credit worthiness of these borrowers and then buyers who took on the risk of buying the loans of the borrowers based on the judgement of these rating agencies got hammered. I am simplifying what was the issue of 2004-2008 crisis. But this is just to give you a very quick idea.