If you want to talk about bad scrolling experiences, then I give you Hacker News. Half the time when there's a submission about some deeply technical topic... before seeing any discussion of the actual topic, you have to scroll through 3 or 4 pages of debate about the ergonomics of the font kerning on the blog post or something.

This is a group of C/C++ hackers who have spent the past 18 years re-implementing Windows 95. The fact that there's any CSS at all on their website is a minor miracle.

I don't know how strongly I feel about non-responsive websites displaying a fixed header bar. However, I'm pretty sure that most people who do feel strongly about it either way aren't going to be using or hacking on ReactOS.