Why we still set justified text badly on the web
Print solved this a century ago. The browser is only now catching up, and most of us are not using what it gained.
Justified text needs two things to look like a book instead of a ransom note: hyphenation, and a paragraph algorithm that optimises the whole block rather than one line at a time. The web had neither for twenty years, so we all learned to set ragged-right and call it a preference.
What changed
Browsers now hyphenate properly, and text-wrap: pretty will fix your orphans without you noticing. That is most of the gap closed.
What has not
Narrow columns. Justification needs room — below about 45 characters no algorithm can save you from rivers of white running down the page. On a phone, stay ragged.