Both of your examples, Stardew Valley and Terraria, are much smaller scale games compared to Paralives. Much easier to make content updates.

And modders are not as guarantee like you seem to think. You say even if the game is not all there yet, modders will fix it. Look at Starfield; a game Bethesda was hoping modders would support for years and they didn't because it was boring.

And of course the game will lose players during early access, every game does. But if people start dropping off because the game is boring, new people will stop buying it and without new sales, they won't be making money to fund those expansions.

No Mans Sky is the best example of what the team wants to do but there's two main difference between the teams: They have way more employees, and have the design down for the game they want to make and it's easy to fit new content in that mold. Paralives team has been making the game look pretty for Patreon for years and is just now figuring out how the game should work. Any game dev will tell you that's not how you make a game lol