You are partially correct, feature creep can definitely ruin a project. However, fact is much of VotV is placeholder content or otherwise subject to change, so expending too much effort on that is likewise a waste. Gradually expanding the scope of a project while ensuring the bugs never get TOO bad is something most developers have a problem with, and this project in particular has been very forward with QA and bugfixing.
And besides, a Roadmap is an option, not mandatory. This is neither a paid project nor a project made under employment, it is clearly someone's passion. Sharing in it is nice, but it doesn't entitle anyone to the labor of the developer. They could pull the plug tomorrow, delete the game off the internet, and no-one would or, could, punish them for it.