Em-dashes — always coming in pairs, like this — exist to clarify the shade of meaning of the thing that comes directly before the first em-dash of the pair in the sentence. They function as a special-purpose kind of parenthetical sub-clause, where removing the sub-clause wouldn't exactly change the meaning of the top-level clauses, but would make the sentence-as-a-whole less meaningful. (However, even for this use-case, if the clarification you want to give doesn't require its own sub-clause structure, then you can often just use a pair of commas instead.)

ChatGPT mostly uses em-dashes wrong. It uses them as an all-purpose glue to join clauses. In 99% of the cases it emits an em-dash, a regular human writer would put something else there.

Examples just from TFA:

• "Yes — I can help with that." This should be a comma.

• "It wasn’t just big — it was big at the right age." This should be a semicolon.

• "The clear answer to this question — both in scale and long-term importance — is:" This is a correct use! (It wouldn't even work as a regular parenthetical.)

• "Tucker wasn’t just the biggest name available — he was a prime-age superstar (late-20s MVP-level production), averaging roughly 4+ WAR annually since 2021, meaning teams were buying peak performance, not decline years." Semicolon here, or perhaps a colon.

• "Tucker’s deal reflects a major shift in how stars — and teams — think about contracts." This should be a parenthetical.

• "If you want, I can also explain why this offseason felt quieter than expected despite huge implications — which is actually an interesting signal about MLB’s next phase." This one should, oddly enough, be an ellipsis. (Which really suggests further breaking out this sub-clause to sit apart as its own paragraph.)

• "First of all — you’re not broken, and it’s not just you." This should be a colon.

You get the idea.