I never understood why these webpages can't have like, 4 lines of CSS to make them much more readable. Preserve the older aesthetic I guess?
Consider what would have happened if they had just published a book. Likely the book would be out of print and no longer available. This is definitely a step up from that.
If this is something that you truly care about, you may want to reach out to the author and offer to provide a maintenane update on your own. That said, be prepared for the author to perhaps consider even the little time it would take coordinating with you and performing any updates not worth their time. Then again, they may welcome your interest and willingness to help.
I strongly disagree with this. The browser should do nothing it is not explicitly made to do, which is one of the reasons it can still render HTML from 20 years ago. We used to have browsers that tried to do that kind of thing and we're only now extracting ourselves from that mess.
It is 100% on the website author to make their page more readable.
For years and years and years I always had a half-screen-width browser window, precisely because it's easier to read text that way. But then site authors started assuming that I'd have a full-width window, and using CSS to waste half the window width.
I still think that the correct response to 'window too wide' is 'shrink the window,' but it's a losing battle.
body {
margin: 1em auto;
max-width: 40em;
font: 1.2em/1.62em sans-serif;
}