It's not my statement, and also please let's not split hairs but look at the actual situation in practice. (Also, RFC-4180 sucks. It only codifies a subset of existing - bad - practice).
The situation in practice is that when people want a “standard” way to do CSV, there is in fact a standard they can use, that does cover most sensible things you’ll want to do with CSV, and addresses the most common corner cases (eg delimeter in field) in a fairly sensible way.
You are free yet to make whatever proprietary extensions or otherwise, at the risk of losing compatibility just as you are with any other standard.
The situation in practice is that when people want a “standard” way to do CSV, there is in fact a standard they can use, that does cover most sensible things you’ll want to do with CSV, and addresses the most common corner cases (eg delimeter in field) in a fairly sensible way.
You are free yet to make whatever proprietary extensions or otherwise, at the risk of losing compatibility just as you are with any other standard.