- They can be as easily edited by hand like other serialisation formats which use printable characters as their deliminators

- It's not clearly defined how you'd use them for non-tabulated data (such as JSON, XML, S-Expressions)

- There isn't any standard for escaping control characters

- They're harder to differentiate between unserialised binary formats

- They can't be used as a primitive like JSON is to Javascript and S-Expressions is to Lisp.

And if we're both honest, reducing the serialisation overhead doesn't gain you anything when working in the command line. It's a hard enough sell getting websites to support BSON and at least there, there is a tangible benefit of scale.

Not that I'm dismissing ASCII records, they would have been better than the whitespace mess we currently have in POSIX shells. However I don't agree ASCII records are better that current JSON nor S-Expressions.