I disagree. Fully justified text was the norm for narrow-column media such as newspapers and some magazines. Ragged-right was the norm for wider media such as printed books because, for physiological reasons discovered over centuries, it's easier to keep your place in long paragraphs. Most web media are narrow-column format, so tend to be fully justified. Whether that's good or not tends to be a matter of how one is consuming the matter: a high-pixel-density phone at 15 cm vs. a 1080p monitor at 45 cm call for different presentation for optimal readability.

> Ragged-right was the norm for wider media such as printed books

What? I'm pretty sure that if I pick any book in my shelf, it's going to be justified.

> Most web media are narrow-column format, so tend to be fully justified.

What #2? 99% of web media is ragged-right, the biggest reason being that it's the default, and that browsers have terrible line-wrapping and historically had no support for hyphenation. And justified text gets worse the shorter the lines are, because there are fewer options on where to insert newlines, leading to large spaces between words. Also, good justification requires fine-grained word spacing control, which doesn't work well with traditional low-resolution displays.

My MSc thesis advisor recently told that apparently thesis documents should be submitted with ragged-right lines these days because it makes them easier to read for dyslexics; while it makes sense, it must be a quite new guideline.

My blog's style has Sakura.css [1] as its base, which keeps the paragraphs narrow on wide displays, limited 684 CSS pixels to aid readability. The justify text-style was a choice by me. Now I really wonder whether that hurt readability.

[1] https://github.com/oxalorg/sakura