The Contributor Covenant is the gold standard for a reason: it is a response to the bigotry and harassment problems that were endemic to the open source communities. Alone it doesn't achieve much, but combined with a good faith enforcement board it helps keep a community a pleasant, joyful place to contribute to, for everyone. And that will increase software quality and attract quality people, aside from being, you know, the right thing to do.
The SQLite developers (developer?) are not interested in inviting more contributors to the table and that's fine, but for a functional public community the Contributor Covenant or something like it is pretty much table stakes.
