Hoi4 doesn't have any diplomacy.Every game over and over again everything comes to world war.
Its 0,00001% probability what world war will not happen
In Stellaris every game is unique,every time world map is not the same.Even if you will set 30 empires what will be spawn every game match wouldn't be same.
Even end crisis and how it's going is unique every game
Btw I played hoi4 for 200-300h,I currently have 500h,mostly done by playing with friends or observation
In Stellaris I have 350h,mostly of that is by solo playing (Stellaris games is way more longer than Hoi4 ones,so some friends doesn't like it)