Misses the point?
I think The Great Torvaldo is making one good point and missing the larger one. It is a scary thought to not be writing on the same platform that you are deploying on. Absolutely right. But it does not follow that you should stay on one, nor that choosing not to is futile.
For one, we can all tell stories of how Production turned out not to be like Dev because the latter had some dll or package that the former didn't. So you already have to have very strict processes for avoiding these types of snafus, and once you have those, you've broken the major objection to cross platform dev.
Secondly, the implication that building on x86 is the only way to establish quality is demonstrably false, when you think about it, there are many, many more non-x86 (eg arm) devices out in the field than x86, and they work well. Phones, routers, etc etc. So clearly the cross-building folks know what they are doing.
I do agree with ARM that having some rocket fast reference hardware would be a Good Thing though. One of the sad changes in Linux over the years has been the gradual dying off of non x86 Linux distros. It would be good to have some decent hw at a lower price point than x86 to resurrect that.