Only works insofar as sites are being nice. A lot of sites do things like: render all text via JS, render article text via API, paywall content by showing a preview snippet of static text before swapping it for the full text (which lives in a different element), lazyload images, lazyload text, etc etc.

DOM parsing wasn't enough for Google's SEO algo, either. I'll even see Safari's "reader mode" fail utterly on site after site for some of these reasons. I tend to have to scroll the entire page before running it.