[RobinL]

I think the fundamental issue is that a single 'cell' (value) can contain newlines, so you can't just assume each line is a 'row' and trivially parallelize.

The problem is perhaps most obvious when you consider that the value of a single cell could itself be a CSV, and this could be recursive

[wenc]

I haven’t worked out if the BNF is unambiguous (RFC 4180) but if you have a CSV in a cell you would escape any ambiguous characters.

An unescaped cell within a CSV will break most CSV parsers in the world even with recursion handling.

https://datatracker.ietf.org/doc/html/rfc4180