When you ask Explorer to navigate to a new location, the steps go roughly like this (vastly oversimplified):
- User initiates a navigation.
- Explorer puts up the "busy" animation and starts looking for the location you navigated to.
- When the location is found, the contents of the folder are switched to the new location and the address bar is updated to reflect that new location.
Any idea why the address bar in Explorer randomly decides to reset itself while you're typing in it?
It's not like Explorer is saying, "Ha, ha! Sucker!" Explorer is just doing its thing, following its happy little checklist, and when it finally locates the navigation target, it moves on to step three and switches the view and synchronizes the address bar to match the view.
If you've messed with the address bar in the meantime, the synchronization of the address bar with the folder contents overwrites the changes you were in the process of making. This isn't an intentional "let's make the user's life miserable"; it's just a consequence of the simple checklist.
Now, yes, it is an annoyance, and yes, it's a bug, but it's not a bug in the sense that somebody wrote code that failed to implement the specification; rather the bug is due to an oversight in the specification itself. This is another example of how things can get extremely complicated even though the basic idea is very simple: Once you have the simple idea working, everybody finds random special cases that force you to take your simple idea and make it more and more complicated.