I do mention that in the second paragraph. My understanding is that most [0] games don't get super-substantial updates making the game leaps and bounds better than it was in its initial state, the way continuously-developed software does. Am I wrong?

[0] Games like Minecraft, Stardew Valley, Terraria and online games being a minority.

Even if a game (or any other software) can be updated later, improving things and fixing bugs is not necessarily a business priority, because you could be adding new features or working on a new product instead.

The profit-maximizing strategy is to keep the level of crappiness that frustrates your customers, but not enough to make them switch to a competing product.