Information

In most grand strategy games the player is provided with an insane amount of information. Usually the player know exactly the amount of troops a nation has, exactly the amount of production power, population, etc. Not only does the player have all information about his own nation, often he also knows everything about others.

In Victoria 3 I am playing Prussia and looking at Chile. We know exactly his GPD, troop strength, population, literacy, and standard of living. In the top bar you see the same values (besides army) for the nation you are playing. You can directly compare them and see which nation is weaker or stronger than you.

In Hearts of Iron 4, you have a spy system, where you can learn more about the actual information of other nations. But here they give you an estimated from the beginning.

One reason for giving the player all information is so he can better act on it. Imagine declaring war on a nation that you severely underestimate. In reality their power is much stronger. Their economy much bigger and their army better trained. This often results in a bad time for the player. Not only will he have no that much fun playing a loosing war. But in most grand strategy games which nation wins a war is determined before the war is declared.

The same is not true for Hearts of Iron 4. There you have much, much more options influencing the outcome of a war while you are at war.

Another reason is that losing wars can be catastrophically unfun and break your campaign. There is a running away feedback loop in most games. When you are stronger you become faster even stronger. If you are weak it takes you much longer to become stronger, in the same time everyone else ran away. Before they were only 2 times stronger now they are 4 times stronger while you just reached their previous power level.

How often did I play with friends Stellaris, they lose one war and say: "That's it, it's over, I can't do anything now". And sadly they are not wrong. Losing one war can mean your empire is now boxed between two much bigger enemies and no diplomacy besides war will change that. Then you will get the Partitions of Poland treatment. Being partitioned is not fun.

How losing a war can be made into something "fun" is another topic.