The point is that the most common thing people do when clicking the URL is typing something else in the search bar, and the second most is copying the URL. In both cases, having the URL change is a problem, because this includes people who
don't know what the
http:// means or what a subdomain is, and
don't immediately understand when a URL is the same as another. Your extra click saves my mother, and millions like her, much more confusion than the click costs you.
You probably mostly know technically fluent people, and think ‘my mother’ is a euphemism, but it's not. If we can get to a world where she can see an unfakeable padlock and read ‘facebook.com’, rather than remember whether it was ‘https:’ or ‘https.’ in the URL bar, and which parts of the string of letters to skip, we've made her life less hostile.
The corresponding problem you're complaining about is incredibly trivial in comparison. If you're actually editing the URL, you see the whole URL. If you need to know these implementation details, they're vastly easier to find than, say, HTTP headers.