I'm a bit confused by what you mean by 'the stable argument'. Please do remember that flarum is developed by volunteers, each of whom have jobs, families, social lives, and other commitments as well. In addition to development, time also goes to moderation, community support, marketing, organizational infrastructure, IT systems, legal matters, etc. We are doing our best to make as much progress as we can, and in recent months, we have been accelerating even. That being said, there are limitations to what we can do, and our current priority is stable.
If you would like progress to happen faster (as we all would), the best ways to do that are to support us financially, find and report bugs, and/or if you're a developer, to contribute PRs and code review.