[KapKap55]

How often do you really need to access the header and navigation "instantly"? In comparison, how often do you need to reread or verify information from a previous paragraph, or review a chart or graph you viewed earlier?

It's fairly obvious which one is actually more important in the majority of cases and it's going to be the actual information you're currently reading through. Obscuring the actual content in any form is a direct reduction to page usability.

[sethherr]

I want to access the menu 100% of the time that I'm using the site I've added the header to, after some scrolling. I re-scroll 50% of the pages that I visit.

Seems like a definite win to me? Maybe your usability desires are different than other users desires? In the case of an autohiding header - it doesn't seem like a big reduction in page visibility?

[DangitBobby]

It's invasive and takes up valuable screen real estate. On top of that, it's very distracting to keep having an element bounce into view. I have a very hide time dealing with even minor distractions on my screen, personally.

I straight up permanently remove most sticky headers with Ublock Origin. 90% of the sites I read content on, I didnt get there by internal site navigation, I got there from a kagi search or HN link. The rare exception are documentation sites; I use their internal navigation often. Thankfully, though, very few of these sites use sticky headers. I just quickly scroll to the top or use the pagination buttons at the bottom.

[vehementi]

I don't think I have ever clicked anything on one of those headers on a website in my life. In fact the anti pattern is so obnoxious I literally couldn't tell you what's even on them.