Well, he's right. Alienware Alpha is the exception, not the rule. Assembled gaming PC are expensive, its a fact. And I think Steam machines missed an opportunity to not offer more things like the Alpha.
I still think they are coming.
I should say, the above is a fairly subjective commentary based on my own recent attempts to just what I consider a good gaming PC in a simple/fast fashion. For me, a 2GB gpu isn't attractive. If you want the higher end PC experience that I'm currently looking for (e.g. a 970-esque system +) it seems like you either build your own or pay a substantial premium that puts it out of my comfort zone. I'm happy to be proven wrong though - I live in the EU, if there are other fast/value-for-money ways of getting a system like that that isn't build-your-own, I'm all ears! (As I say, I'll probably end up building my own anyway if not, but the lack or obscurity of other options is lamentable).
you being in Europe sort of makes things more difficult, because alienware products are more expensive over there than over here. Case in point, at one time, you could buy the Alienware Alpha for like $199 with discount.
I think the value proposition you are asking for will come in time, just like how as time went on last generation, it became easier and easier to build a console-busting rig at an affordable price. We're still technically early in this generation's life span. In another year or two, I think you'll see much more competitive hardware.
But that's not the performance tier that most enthusiasts on GAF will want.
It's within the ball park of the PS4 and Xbox one. I would say someone buying an alienware steam machine
isn't an enthusiast, and given that people pick up Xboxes and PS4s, it's within an acceptable range. It's not really an outlier in terms of what it can or cannot run, like say the Wii was compared to the Xbox 360 or PS3. It'll still run the same games. It's not a whole other class of hardware.
But what you speak of is another problem people have with PC gaming - the idea that PC gaming is the same thing as console gaming, just with higher end specs. The PC is it's own platform, with perks beyond running games prettier with bells and whistles. I'm obviously preaching to the choir here, but there is a lot that's enticing about PC gaming even if you're merely on par (or even slightly below) performance of the competing consoles. Game sales, mods, free online, etc. The same reasons someone chooses an either Xbox or PS4 over the other - there is value in the ecosystem.
Also (and you certainly know this is true) - the value proposition for machines like this will grow over time the longer you hold off on buying. In 2 years, the value of an equivalent alienware steam machine at the same price will be better than it is today, because of the way technology becomes cheaper over time. Consoles don't really dip in prices the way I expect PC parts to.