I use an extension called "Bar Breaker" that hides these when you scroll away from the top/bottom of the page.[0] More people should know about it.
[0] https://addons.mozilla.org/en-US/firefox/addon/bar-breaker/
I'm happy to learn something new about other people's preferences, though. If people prefer scrolling to the top, so be it!
EDIT: It occurs to me that this could be a preference setting. A few of the websites that have let me have my way, I've started generating CSS from a Django template and adding configuration options to let users set variables like colors--with really positive feedback from disabled users. At a fundamental level, I think the solution to accessibility is often configurability, because people with different disabilities often need different, mutually incompatible accommodations.
Unfortunately, the web today has strayed far from its original vision. Yet, we continue to rely on the foundational technologies that were created for that very vision.
If browsers catered to their user's desires more than they cater to developers, the web wouldn't be so shitty.
The primary benefit of web applications is they don't lose your data. Not a single web application UI that exists provides as good a user experience as the native desktop applications that came before. A web where browsers provided their own UIs for various document types, and those document types could not modify their UIs in any way, period, would be a better web. You serve up the document, I get to control how it looks and behaves.