"As entities like Countrywide are not regulated as banks."
Yea, which also means Countrywide wasn't regulated under Glass-Steagall or other laws in the first place, so I could use Countrywide's example to argue all of the deregulation that happened in the 90s can't be blamed for the subprime crisis either. Or Bear-Stearns', or Merill Lynch's, or other investment banks. We're talking about factors tangentially affecting the collapse here.
You're conflating two completely different things: loan origination and mortgage securitization.
The right wing talking point is to blame the government for encouraging forcing banks to ORIGINATE loans for low-income borrowers. I'm sure you've heard of ACORN. In Right Wing, Looney Bin World, uttering the word "ACORN" has the same potential for causing a conniption as saying "Planned Parenthood" or "equal pay". As a non-bank, the Countrywides of the world were not mandated to offer any such loans. Regardless, ACORN loans are far less risky than the subprime crap issued by Countrywide. Countrywide issued these subprime loans based on its own initiative--not the government's.
As a non-bank, Glass-Steagall doesn't apply to Countrywide either. What Glass-Steagall does apply to are the investment banks that SECURITIZED the subprime loans. Because of the repeal of Glass-Steagall, these investment banks were allowed to merge with large commercial banks, and when these investment banks started buying up all the subprime mortgages issued by Countrywide, they put the entire commercial banking industry at risk.