On nautilus you can’t even click the address bar. On dolphin it still works as you say.
I didn’t even realize this until you wrote it down. That is bad. It’s the same on mobile. Consistent behavior is good. At first you select the box and then write into it. It’s good that it selects everything, otherwise you would have to select everything in order to be able to use it as the search box. It would be very annoying if it were differently.
That leads me to the question: why aren’t we using the path box to search stuff like on browsers? Dolphin even opens firefox and searches for “test” when I type just “test” into it. Why is http the default protocol?