Might be moot with texting altering the whole language, but I always thought the em-dash was used in conversationally-toned writing to indicate where a speaker would pause. Formal writing should probably stick to conventional punctuation.
Check out this article from Harvard’s newspaper:
https://www.thecrimson.com/article/2025/5/28/inside-war-with-washington/
FORTY EM DASHES!!!!
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I tnink its where the sriter pauses, Then switches thought-kinda like Tim grabbed the gun—his eyes never leaving the stranger’s—he shot the fella before he could unholster his pistol. (Or something like that i think)