The issue with that at the time was that Microsoft was using temps to avoid paying payroll taxes. Ironically the IRS wised up to this tactic because of just how good Microsoft was treating their temps, i.e. the same as regular employees.

Now the issue is a company is using temps to hold down the market rate for salary. Less about tax avoidance, and more about wage suppression. Of course it’s also a valid argument to say the Supreme Court decision at the time made it more likely for companies to choose this route.