The fault is on both sides. These people were careless to be sure, but they were also lied to.
This sort of thing will wind up getting laws passed that will limit the financing options for the competent, too.
Of course it is, in the macro sense. But in the particular loan in this story, the borrowers were fools who overreached themselves to buy more house than they could afford. If they didn't understand the terms of their loan, it's because they didn't want to, lest their conscience intervene and talk them out of the house they knew they deserved--whether they could afford it or not.
I don't see where that happened.
Percentages, rate and interest are taught in the fifth grade. These people wanted to believe.