Even if we had unlimited computation, there are human factors that are tough to determine beforehand. For example, some originators encouraged their borrowers

Even if we had unlimited computation, there are human factors that are tough to determine beforehand. For example, some originators encouraged their borrowers to lie more, and now post-meltdown some servicers are less willing to agree to loan modifications / short-sales. At first traders didn't place much emphasis on the originator, servicer, or bank, because they focused on the loan stats (FICO score, loan type, interest rate, etc). Post-meltdown, the smart players see obvious systematic patterns between originators and servicers, even given the same paper stats. But again, to see it before it happened, it's less a computer problem and more an unscalable human due diligence problem.