I agree with your last sentence, but not the one before it. Alex isn't arguing that users consciously prefer native apps; most don't even know what "native app" means. He's arguing that native apps feel better to users and that this feeling is worth something. How much it's worth is hard to quantify. The test you describe wouldn't answer that. As for this:
which all available evidence says is one account worth $20 a month
... surely you haven't reviewed all available evidence on this question? Or did God give it to us when he gave us AB testing? I'm joking, but I think you're trivializing a nontrivial question. I'd like to know how to find "all available evidence"; my experience is that this kind of thing can be very hard to measure.
Edit: it's worth remembering that Steve Jobs made almost an identical argument to Alex's in his critique of Flash last year, even emphasizing that it was his most important point: "We know from painful experience that letting a third party layer of software come between the platform and the developer ultimately results in sub-standard apps" (http://www.apple.com/hotnews/thoughts-on-flash/). Sub-standard apps are exactly what the OP is about.
which all available evidence says is one account worth $20 a month
... surely you haven't reviewed all available evidence on this question? Or did God give it to us when he gave us AB testing? I'm joking, but I think you're trivializing a nontrivial question. I'd like to know how to find "all available evidence"; my experience is that this kind of thing can be very hard to measure.
Edit: it's worth remembering that Steve Jobs made almost an identical argument to Alex's in his critique of Flash last year, even emphasizing that it was his most important point: "We know from painful experience that letting a third party layer of software come between the platform and the developer ultimately results in sub-standard apps" (http://www.apple.com/hotnews/thoughts-on-flash/). Sub-standard apps are exactly what the OP is about.