If they were popular they'd be supported in your editor though.
Also, the fact that they have been around for years and never taken off implies that they probably never will.
Realistically I don't think anyone (at least on HN) would presume that editor support would be so weirdly obtuse, but it's not exactly well-defined here, either.
I'm mostly just thinking out loud, here, not really critiquing anyone.
[modifier]-[C,D,E,F]
FS: ^\ GS: ^] RS: ^^ US: ^_
Since these delimiters are not much used, on many terminals ^\ is mapped to send SIGQUIT. Use 'stty quit undef' and you can then type this at the keyboard. This works on Linux and OS X, and likely most other systems. Note that with most keyboards you are also using shift for RS and US. For emacs, prefix with C-q so that it inserts the literal.Other posters have noted that they have ASCII separators recently, I have as recently as 2018 internally at a FAANG. So they are not completely unknown in the wild.
Who's writing CSV files by hand though?
I'd expect some kind of CSV mode in my text editor where Tab and Newlines are turned into keys to insert those characters