My main argument for releasing major versions no matter if the product is “done” or not is that it should help grow the community as major versions attract both more users and more developers to the project.
I believe that home automation is a type area that will continue to evolve as long as the human race will use technology so there will always be breaking changes and major shifts in focus, so I don’t think that large products like these will ever be “done” as then they would be no release to release a 2.0 or 3.0 version of anything either.
Kodi (XBMC) is an example of a more popular open source software which is now on ver. 19.0 Alpha
They too have a software that will NEVER be seen as “done” because the different needs it fills are moving targets. Sure, their GUI is much more user-friendly today then it was when they release 1.0 but it is still not user-friendly enough for many non-technical people out there, however non-technical people are not their target audience, so in that respect their project goals are probably somewhat similar to that of the Home Assistant project.
I think that releasing major releases has made a differnce to Kodi/XBMC as they by doing so get larger articles in the press in the media and loads more blog posts with each major release which is something that I believe they have helped them gained a lot when building their community which seems to have grown much bigger each year then it would have without those extra press articles and additional blog posts.
Again, more users joining the community usually also mean more developers joining the development, which is something that I think anyone would agree benefits everyone. Large projects like these are never “done” so there will always be a new major release as long as developers keep working on it.