Absent the etymology described in this thread, I would have had a similar confusion to theirs as to what distinguishes this scam. But now I know it's a regional term for it and I shouldn't necessarily expect a term with an obvious connection to how the scheme works.
It's called pig butchering because the scam relies on a long con where the scammer often "feeds" the mark with either real or fake small wins to entice them to provide more money to the scammer. They're "fattening" the pig.
