I bought the alpha version back in 2015. I was happy with my $15 purchase then and they have continually updated the game. Sure, it has taken a while to “complete” the game but I never really even expected a story mode.
I do kind of agree with the sentiment that games so not necessarily need to be constantly worked on. Another game I think of is No Man’s Sky. Yes, it was a shallow and incomplete game on release. But they kept working on it until it was far beyond what would be considered complete. And they are still doing pretty major updates. While I do appreciate it because they have added some great content, I also think they could call it good and possibly put their developers onto a new game. There is also the risk that a major update screws up the game that people thought they bought.