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
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