This means that records must not contain either of those two bytes, or else the format of the table will be corrupted. And unless you're producing the data yourself, this means you have to sanitize the data before adding it, and have a policy for how to respond to invalid data. But maintaining a proper sanitization layer has historically been finicky: just look at all the XSS vulnerabilities out there.
If you're creating a binary format, you can easily design it to hold arbitrary data without escaping. But just taking a text format and swapping out the delimiters does not achieve this goal.
