They don't, but they were established for a singular reason, to shepherd the term "open source". A term that was chosen on terms of having little previous use. They did not succeed with the trademark application because the term was deemed too descriptive, not from a lack of trying. So we should probably respect their term if we want to use it. There are plenty of other terms you can choose instead, such as "permissively licensed software" which also has a de facto established meaning.

> The OSI doesn’t represent everyone.

Sure, sure. But the term Open Source has a meaning. Ultimately terms have meaning based on their usage in the language. For 'Open Source', its usage happens to reflect the same meaning enshrined by OSI.

> It is maximally permissive.

It appears that there are now several redis forks, with several licenses. For the most part: everybody wins. If you prefer the MIT license, maybe you would prefer to contribute to the BSD-licensed Valkey. And if not, you can fork redis too.