The "credit rating" systems in the U.S. are bullshit capitalist tools to keep poor people poor and push wealth into the hands of the elite.
With poor credit in the U.S. you will have a hard time finding anywhere to rent or purchase, find it hard to purchase any sort of transportation, can be summarily ordered to pay debts with predatory lending rates you have no money to pay, and possibly have everything you own taken.
It's just the modern upgraded version of serfdom.