Even though Early Access can be an incredible thing to allow developers to build up their game with the community, and pull in some early funds, it can also go very wrong. And now Valve are making it a bit clearer for you if a game hasn't been updated.
Yes and then they have released like one meaningful update in 4 years.
They’ve had a few actually. Three new biomes (plains wasn’t really a thing when it first released), three new bosses for those biomes, all kinds of structures and craftables, some new mechanics (you can lay siege to Ashlands fortresses + magic)
It’s gotten quite a bit of love over time. Just not as often as some other games. Which is fine, because it is still actively being worked on.