>He cited Greenplum, which used PostgreSQL as the basis of its data warehousing system, which he said limited success. "They were going to be so good, they said that, 'We don't need to stay with what the community is doing'."
I'd argue Greenplum failed because the company behind it had limited experience in building and selling data platforms and were never particularly well-funded, so they struggled to eat into Teradata's business. They were then were very *very* rapidly overtaken in price-performance first by the Hadoop-adjacent query engines and then ultimately the cloud native database platforms. All of which were and are "single vendor" products.
Lack of community had nothing to do with it.