Is there any concrete data showing whether this has any effect on the readability or comprehensibility of text content?
Good question, but keep in mind that it's claiming to `text-wrap: pretty`, not `text-wrap: comprehensible`. That should be enough!
It's claiming both:
> we want you to be able to use this CSS to make your text easier to read and softer on the eyes, to provide your users with better readability and accessibility.