Sometimes I wonder whether advocates for heavy client-side JavaScript ever bother to test on mobile devices, because it very much seems that in the majority of cases they don't. The vast majority of JavaScript-based "show HN" submissions I've seen don't work on mobile browsers well or at all, to the point where I've been trained not to click them. This submission from a few days ago is an example, and last I checked it caused browser crashes and, even if you managed to load it, was unusable with an iPad: https://news.ycombinator.com/item?id=6270451

Edit: Here is another example from the past few days that's unusable on mobile: https://news.ycombinator.com/item?id=6302825

This is a common problem with media sites. I dread trying to load quartz, usa today, gawker, etc since every thick-client media site is intermittently a bad citizen on mobile browsers (for example, gawker in Chrome on iOS currently perpetually reloads the page). Even when these kinds of sites work, there's often a multi-second delay where where the user has to sit and watch elements fly around as the page is built.

Edit again: just to be clear, if you are a non-technical product manager or CEO type, my comment should not be interpreted in any way as an implication that the web or JavaScript is somehow inherently bad and therefore your developers must build a "native app." My comment's intended audience is developers with a deep, working understanding of these technologies.