This is simply false, there are plenty of complex apps with varying degrees of usefulness but they certanly don't reduce to 80's game clones and few screen apps. And even if it was true it's not a result of anything intrinsic to the app model. Also "tight control a la Apple" indicates that you missed his point.
How many times did you do make and sudo installed shit on your system to get basic app that should for all intents and purposes be walled of in a sandbox ? Even without sudo why should install script have access to my personal files without explicit permissions ? Did you run in to a situation where you wanted to install the latest version of an app for your system but it wasn't in your distro repo so you decided to build it only to find out that your repo GTK+ library was out of date and your options were rebuild all GTK+ packages or update the OS to alpha ? Even I gave up at that point - imagine the average user wanting to get the latest feature advertised on his favorite app site.
I use Linux desktop daily but it can be a hell and you need to know how to wrestle with the system, it's certainly not idiot proof - and it needs to be for mass adoption. But then again "mass adoption" (IMO) shouldn't even be considered a realistic goal, being useful to techies/developers and available on servers is a good objective too.