
You are wrong
OK so you're right for now. That IS how things are but it won't always be the case. Imagine a world of applications in the cloud... Some say this paradise already exists...
One day the user will be used to their applications opening in a browser. What happens then? Well, in short: The operating system becomes as it should be, irrelevant.
As long as you have a web browser everything else is unimportant.
Last time I looked, Firefox is pretty multiplatform...