Since it predates CSV, it wasn't an alternative to it: it was the original. I suppose the Excel or 1-2-3 team either didn't know about the separator characters

Since it predates CSV, it wasn't an alternative to it: it was the original. I suppose the Excel or 1-2-3 team either didn't know about the separator characters, or they did but then-current text editors weren't useful enough to do anything with them (and user-editability was important). It's a real shame: with a more integrated system, they could have added functionality to the editors to understand ASCII record encoding, and CSV need never have existed.