Regular releases encourage contribution
As well as writing and maintaining my open-source software projects, I regularly contribute to other people's - including PHP libraries, Drupal modules and Tailwind CSS plugins.
I'm more likely to contribute to your project if you release new versions regularly.
Why would I if my changes may sit on a development branch for a long time or not be released at all?
If I can see that my changes are likely to be released soon, I'm more likely to spend the time and effort to contribute instead of looking for a different solution.