I'm not super sure but you probably could've used one instead of the comma in your last sentence. I think people just use other symbols instead: comma, dash and period.

I think Germany does that as well. It was very confusing to inherit code that "accepted CSVs", but didn't accept files where the values were comma-separated.

Because we use the comma instead of the dot for decimal numbers. Since the advent of computers it's a bit less true, dots are used too but this is the historical reason.