Yes, they would.

This is about competing in the console space though, where eating some of the cost of the hardware is a common practice on the gamble that the more consoles you sell, the more you make in game sales.

The problem for Valve is that they're selling something that could be used as a general computing device which means that there's no guarantee that they'd recoup the cost in game sales.

This is a sort of middle ground. I understand what I think you're saying, that if someone buys the console, and sells the voucher, Valve only stand to recoup $60 with no further game sales...

But on the flip side, that's a lot of extra bs for a call centre IT department to have go through to list and sell a hundred plus vouchers, if they even manage to sell them. It could happen, but it's far less appealing than a nice cheap workstation for $700. Any they can't sell before the vouchers expire is a machine they've paid full price for. It makes it a much riskier and more burdensome prospect.

On the consumer side, someone weighing up a $500 playstation and a $900 steam machine is more likely to seriously consider the steam machine if they get $200 of that back in games