Well… if you have ever supported a desktop app you know how difficult “version dispersion”, users that never update their OS, users that always update their OS, different hardware, other hostile software, etc. can be. If you know, you know.
Sure, I'm not saying it's easier. It would be completely stupid to go down the webapps road if the desktop apps one was both better and easier.
I kind of find it ironic, though: why not write one desktop app that only supports the latest version of Windows, and tell your users to use that? If you're big enough, surely you can force them to use the OS you want, right?
I am convinced that most people who love webapps kind of hate the idea of being forced to use the latest version of Windows. But somehow they find it okay to force everyone to use Chromium? What's the difference?