They do, and it's even misapplied in this example - there are weird hard line breaks (an ASCII character) in the wrong places, breaking the supposed "accessibility" of the format.
But also, you continue to miss the point - this lacking/bad layout/formatting is precisely the reason not to use plain text
>But also, you continue to miss the point - this lacking/bad layout/formatting is precisely the reason not to use plain text
I don't miss the point, I rather disagree with your opinion.
Formatting and layout are properties of the client, and you can display plaintext in any color or font you wish.
But the default - plain white background and plain black text with a simple serif or sans-serif font simulating a paper document - is perfectly readable.