Earlier quoted context omitted.
JSON/JSONL is not self-describing for many of the most common tabular data use cases. There's no date type or currency type. If you are going to displace a standard, it has to be significantly better than the old.
CSV does not have date or currency types. Those are an Excel conventional microformat overlaid on top of CSV. The semantics of CSV — how it decodes, if you don't have an application making additional configured assumptions or using heuristics to detect microformats — is just N columns, one of header names, N of raw text cells. Nothing more, nothing less. No schema defining what a column's type is.
If you want something better than CSV to take off, at the very least it needs to solve the common pain points of CSV. JSON doesn't - all it brings to the table is the ability to distinguish number vs text. That's a yawn.