The point is that it's a variable cost, and that, depending on the total quantity of talent (i.e., project scope multiplied by various specialty skills required

The point is that it's a variable cost, and that, depending on the total quantity of talent (i.e., project scope multiplied by various specialty skills required), it can make more sense to rent than to employ that talent. Most outsourcing is not about hiring cheap, low quality foreign talent. It's about hiring highly skilled teams to fill specific functions for specific projects, which can be much more reasonable than employing all the necessary talent. If you are renting talent and it is cheaper per hour than what it would cost to hire qualified talent as an FTE, and the product that they are making is a core competency for your company, you may be treading on thin ice. If you don't have the technical skills to judge the work produced (for example, I don't), you may be in the process of falling through the ice.