Earlier quoted context omitted.
"It is (and, increasingly, was) used to signify that a bibliography entry has the exact same author(s), editor(s), translator(s), or corporate author(s) as the previous bibliography entry." https://danieljtortora.com/blog/3-em-dashes
That is so stupid. Absolutely does not deserve a new character just for that(especially one that is so unusually large). Whoever introduced that is absolutely drunk on power. The only reason that exists is because of a power discrepancy where the people with powers to create new characters are also the ones who do enough writing that they feel such a specific and niche pain.
If not, I doubt some typesetter in the 19th century (or earlier) was so drunk with power when setting out the lead type to make the 3-em dash.
EDIT: Additionally, unicode primarily exists to encode the typographic symbols that exist—that is to say, it's a catalog of what already is. Take Ogham[1] for example.