I would rather let a few people scalp some devices then give up ownership over the devices I buy. I would not want valve to have a remote way to brick something I have bought.
The fact you need an account in good standing and it's limited to one per address helps a lot in cutting down on the number of devices that can be scalped. It is basically just a few individuals that can do that and not a few people systematically buying up all the stock at once to resell.
I would rather them focus on upping the supply then preventing every single scalper.
Yes it is a problem. But a temporary one that IMO is worth the tradeoff. You might not get multiple devices up front but that means other people can have a device at all. Why should you get 3-5 devices and stop 3-5 other people from having one at all? You can share a single device for several months while the initial wave die down and stock is able to be replenished. Then they will remove the restrictions and you can get multiple devices. In the meantime it means more people can get a device and helps to stop scalpers from getting them all. It is a tradeoff, ideally it would be better if there was enough devices for everyone that wants one to get one. But you can only scale production up so fast.