Your browser can cache a web app to be used offline. Plenty of Chrome apps are packaged this way. Firefox also has an option to do this, and Firefox OS can wo

Your browser can cache a web app to be used offline. Plenty of Chrome apps are packaged this way. Firefox also has an option to do this, and Firefox OS can work without an internet connection. An HTML5 app is just source code obtained from a website that's run through a VM, and may or may not connect to a back-end (usually does though). The problem isn't the web, it's how many web developers choose to use it. If you want to really know how powerful the web is, check out many of the WebGL demos and game demos out there...