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that's the point: sometimes there is no tl;dr.
Formatting, fonts, colours, structure of argument, visual aids.
Clicking [reader view] on this article aided me immensely in being able to take it in. As one of the many ADHD people who encountered this, the white on black, wide page, and a serifed font were all non-informational aspects of the page that made it difficult to take in.
You are wrong that sometimes there is no tl;dr In the absence of someone putting in the work to make content accessible the emphasis merely falls upon the dr of tl;dr.
No-one requires you to make things for everyone, but you cannot expect to reach everyone without consideration of them either.