"I've run a team of Solaris sysadmins and yes I could have hired Linux sysadmins…"

Now you're comparing system administration to design - this doesn't really work. Technical skills like this don't translate well, and I never claimed they do.

The post is about UI and interaction design and those principles are the same across all platforms. Design patterns for a specific device, operating system, or medium (e.g. the browser) are not something you need to be a specialist to learn, analyze, or pick up - you need to understand the fundamentals of design.

Early iPhone designers who built great apps had spent much of their careers designing on the web. They had to learn and come up with new design patterns, but since they were good, it was well within their skill set.