Comment by tyrabound
16 hours ago
It's actually not em-dashes, they are en-dashes, which is either intentionally to deceive (e.g., swapped) or used incorrectly. Both of which are bad, it's up to everyone to decide on which is worse coming from MITality.
Spaced en dashes – like this – are a correct and accepted typographical choice. Whether to use spaced en dashes or (spaced or unspaced) em dashes is a matter of taste or local convention, and varies from one publication to another. Other than a typo or two where the space was left out on one side of a dash, the dashes in this linked document are just fine. See https://en.wikipedia.org/wiki/Dash#En_dash_versus_em_dash
I was not claiming they are not correct punctuation/syntax. My claim is just no one uses them that frequently... When you see dozens of them in the first few pages of a document it raises suspicion.
This is likely an artifact of writing standards - not especially suspicious, it's like MIT Tech Review or the New Yorker using diaresis when they need to say reëducate.
Some authors use a ton of dashes, while others never use dashes.