Early access is a descriptor that isn't too useful except to say the developer doesn't consider the product finished for a 'first' release. Some developers will label a game as completed when it has serious issues that prevent most from having fun. Other developers will label a game incomplete even though there are dozens of hours of enjoyment to be found. A better judgment is to ignore what is promised, and instead ask if the game as it currently exists justifies the price. In the case of Rimworld, that was a yes for me. It may not be a yes for others. That's fine; we all have different preferences.
Take a game with a lot of free updates, such as Terraria. Consider the game the day it was released. What if it had been labeled 'Early Access' and incomplete because it doesn't have all the features that were given in post-release updates? That wouldn't make it worth any less on the day it was released.
The problem, as I see it, is that the nuance you're talking about isn't visible from the Steam store page. When I see a game that's Early Access, there's not a lot to indicate to me:
a) How far through the QC process the game is
b) Whether the game is going to change dramatically in the next 6 months
c) Whether the game is about to be a cancelled project.
d) Whether there are features/portions of the game that will just _not_ work with <insert OS version/hardware/network configuration/...>
Basically, Early Access is too big a tent to be meaningful, except to take as a caution of "you might be paying for vapor."
Take a game with a lot of free updates, such as Terraria. Consider the game the day it was released. What if it had been labeled 'Early Access' and incomplete because it doesn't have all the features that were given in post-release updates? That wouldn't make it worth any less on the day it was released.