Do you know why they have this philosophy? Why would they not accept patches and pride themselves on having few contributors? Seems very odd.
If we accept patches, then the person who has submitted the patch owns the copyright on that patch, and that means the software is no longer completely in the public domain. Unless, of course, the patch submitter has filled out a lot of legal paperwork to dedicate their code to the public domain, which rarely happens.
It's hinted in the linked page:
> In order to keep SQLite completely free and unencumbered by copyright, the project does not accept patches. If you would like to make a suggested change, and include a patch as a proof-of-concept, that would be great. However please do not be offended if we rewrite your patch from scratch.
Because they can sell licenses that way and make money off the product.
"Open-Source, not Open-Contribution: SQLite is open-source, meaning that you can make as many copies of it as you want and do whatever you want with those copies, without limitation. But SQLite is not open-contribution. The project does not accept patches. Only 27 individuals have ever contributed any code to SQLite, and of those only 16 still have traces in the latest release. Only 3 developers have contributed non-comment changes within the previous five years and 96.4% of the latest release code was written by just two people. (The statistics in this paragraph were gathered on 2018-02-05.)"
https://www.sqlite.org/copyright.html