A bank isn't an individual who is lending his own money. It is an organization that lends other people's money and needs a veneer of justifications for the choices they make, and credit reporting agencies are a perfect choice. You mentioned earlier that banks have statistical teams making these analyses, but most simply don't because that provides counter-information that undermines the whole value of credit reporting agencies (which is that they outsource the politically fraught choices and makes it easy to say "well we just followed their ratings, just like everyone else").

Regarding the subprime crisis, the biggest victims were the largest banks -- the most sophisticated being put completely out of business -- so not sure what the bit about pension plans comes from (many of those made a lot of money on it).