The DAR isn't just a club, it's an information source. The DAR isn't the ideal source of information on a person's Revolutionary war service (it's better to access the original records), but it's worth checking for a number of reasons. The DAR database is pretty easy to access and cite, and it's a better reference citation than some unidentified person's "DAR files." The service-record information in the database is succinct and can be more understandable summary than what we might see in other sources. I've seen several cases where the DAR database indicates that the research records or genealogy on which somebody joined the DAR in the early 20th century (or later) are no longer accepted as valid.
And Johannes Kortright's profile still does need "More Records," including (but not necessarily limited to) transcripts of the baptism records for his children and baptism records where he was a witness. His profile is still based almost entirely on secondary sources that generally don't cite their sources (not to mention that it cites "from Cartright Family Home Page" without clearly indicating which information came that source, nor any indication of what this website is), but primary records should be available. The church baptism records I mentioned are primary records that are often valuable for filling in a person's life details and establishing various family relationships.