Brands could do that - or an approximation of that by having an higher launch prize for the initial batch - yet they mostly don't.
Maybe the intent here is not keeping difference to themselves, and there's more brand value in not profiting from supply constraints, while being perceived as doing something about mass scalping.
Since most brands don't seem to agree with you, and if you just feel like you should be able to use your extra money to get lucky, you can still try to convince one of the lucky ones. I guess the few who might take it to eBay will charge even more for the privilege.
Not everything needs to be about efficient markets.
Giving a list price would make no sense in the case of an auction, in fact would be misleading, (maybe even illegal ??), and not just because of these issues.
Most people would bid the maximum that they can justify. That's like saying that only scalpers take part in auctions (easy counter example : eBay).
In real world, sales tactics work. People can be influenced to pay more than they thought they're willing to pay. Scalpers know this and exploit this at scale. A Vickery auction gives basically zero opportunity to get talked up. People will bid at the "thought they're willing" price, and scalpers will outbid them. Then the same people who underbid on auction will go to eBay, see it listed at "influenced to pay more" price, and buy it for much more than they bid.
And yes; the vast majority of eBay auction bidders are indeed scalpers, whose day job is to look for cheap deals that they can resell for more. It's extremely rare in this day and age to actually take advantage of eBay bidding to buy in-demand stuff on the cheap. It's much easier when there's "buy now" option but you need to be fast and lucky because you're competing against scalpers here too. Of course things are different for stuff that few people want in the first place - scalpers are not interested in those because they're too hard to offload, so you get your fair chance.
The corollary to this lottery will ensure that people who want Steam Machines day 1 actually get them at cost. So not only does this negatively impact the supply-side of scalping, but it also impacts the demand-side.
With the lottery, a good chunk of those systems are going those who would be willing to pay markup for them, but didn't. So the lottery does double-duty - it kills scalper supply and demand for scalped units.