The cause is you got used to comically small text. That site is fine readable size (unlike the interface we are exchanging opinions on). Though it is still readable on 80% zoom, slightly eye straining on 70%, but it is far from oversized.
I consider the reasonable range of body text font-sizes to be 16–20px, but I recommend 16–18px. (On small screens, you should exclusively use 16px; the larger values are for larger screens where it can be warranted and I would almost always recommend it.) This is what just about everything is calibrated against, so you cause trouble by going much out of this range.
HN uses 12px. At 25% below the range, this is significantly undersized, and 120% scaling is about the minimum I can tolerate (though I don’t find myself going up to 133% for some reason, which I might have thought I would do, but I decided I didn’t like it).
The site in question uses 25.3px. At 26.5% above my proposed range (and 40% above my recommendation), this is significantly oversized.
If your eyes are straining at 70%, which reduces it to 17.71px, something’s wrong, probably in your setup—because that’s generally still at least 10% larger than all the rest of the text in your OS! (Linux/Sway: Firefox UI seems to be largely 14.667px with a little 15.4px, and this 14.667px seems visually to match other apps.)
No, creata is correct. This site’s text is very unreasonably and troublesomely large, and even shrinking it to 80% leaves it very mildly oversized.
(The lead paragraph is 32.2px, which does reach the point I would happily describe as comically large. The quote a couple later is 21.85px.)
I need to put it at 70% while leaning back to not strain my eyes. 40% is when it finally gets smaller than here (which I find just right) and could become eye-straining for me in the other direction.
He explained this once, but it's been years and years and I don't have a source link. His argument for using the large fonts hinges on the fact that you keep your desktop monitor farther from your eyes than you do printed materials like books and magazines. Accounting for these distances, a 16-pixel or 18-pixel font size on screen is similar to an 11-point or 12-point font on printed material. Somewhere on his site, I think he has a demonstration with a photograph of a book in front of his monitor that illustrates this, and it looked pretty convincing.
This argument is unsound: CSS already takes that into account. All of the units (px, pt, mm, in, &c.) are, for screens, defined in terms of a reference pixel, which is the visual angle of one pixel on a device with a device pixel density of 96dpi and a distance from the reader of an arm’s length. https://www.w3.org/TR/css-values-4/#absolute-lengths has some more explanation and diagrams that demonstrate what’s going on.
No, the reason why it’s customary to boost the font-size a little on larger screens is because otherwise things start to look silly because you’re using such a tiny part of the space available to you, and you have a larger viewport, so you can increase the size a bit without losing too much from the screen at any time. But if you take it too far, it starts to look silly for different reasons, because it’s unreasonably large (and more importantly, inconsistent with common practice).
There is just one big problem with that - I use a Laptop and not a Desktop, which is a similar distance away from my eyes as a newspaper. The result is a website where everything looks like it has the size of the headline of a newspaper...
I guess in 2006 the resolution of monitors wasn't the same as it is today meaning (if the website wasn't updated since then) it was never tested on a 14 inch near 4k display.
Although, I'm not sure how they can read text on UI elements at the same time.