> “ Do you really believe that "parse CSV to a data frame" and "parse CSV to a parquet file" and "parse CSV and apply a query to it in-place" are completely separate, unrelated things?“

Yes, absolutely. Very high level design goals are completely different between those use cases and you would be forced to make mutually exclusive trade offs to solve any one of those problems - which will directly lead to concessions in terms of the other use cases. No one generic csv parser can be optimal to all three.