To me, the semi-transparent header and border are absolutely unacceptable. Imagine opening a book and 20% of the page are decor, decor with text no less. In clear words: this fucks with my attention, and the reason is that this is design that serves no actual purpose. If you're building a house or a product, anything that's not necessary is detrimental to the users experience, I don't even understand what can be argued about this
> Imagine opening a book and 20% of the page are decor, decor with text no less.
Regularly happens in "book world". Chapter headings are often an entire page, and sometimes even a double spread. The average whitespace around headings on the three closest books at hand were all 1/3rd of the page, making that decor even greater than the 20% you're describing.
House of Leaves is a book like this and the story is not the same without it. The words move down the page in a staircase fashion as Will Navidson is walking down the stairs to his untimely demise, in one example.
I've never seen anyone care about reader mode. Most websites are semi broken in reader mode because reader mode has some weird custom logic to it about what does and what doesn't show up in there. There are no public standards to follow to accomplish what you want.
You can't expect everyone to reverse engineer your browser to make your reader mode experience better. Reader mode is explicitly a client side algorithm, parsing and displaying a document for you, the user. If reader mode doesn't work right for you, you should file an issue with your browser maker. After all, they're the ones that designed the algorithm to partially hide the contents of the web page for you.
For what it's worth, I have no issue viewing the images in Firefox's reader mode.
I can't see any super distracting content on this page anyway. There's a black side bar and the text is almost black on white. Perhaps you're referring to the header, but even that's mostly white and black. There are definitely some places where accessibility can be improved, but this is hardly "not acceptable".
I actually don't think this is about personal preference. If you build/design something with components that serve no functional purpose, the result is just going to be worse. Classic architecture learned this lesson many, many generations ago.
If it is my website and my resources and my words I'll design it in a way that I prefer because it is my creation, my style. If that offends you then find someone to transcribe it for you. Don't look a gift horse in the mouth.
reader-view doesn't show the images, and for me the webdesign is too hostile to read the content without reader-mode.
Please don't build websites that are attention-expensive to consume, everything about it is terrible.
If your content is text, ship it on a neutral background, everything else is not acceptable.