Query strings and hashes are a little different, since those may contain information you might not want to scrub.

"Vanity" paths in particular can be rewritten because you often have a "correct" value for a given route.

e.g. https://community.nodebb.org/topic/180/who-is-using-nodebb

You can rewrite the tail end of this URL to whatever you'd like but it will always redirect you back to the correct canonical slug.