When playing No Split games, players should be able to press enter to confirm an attack/move order, which is more convenient. Otherwise we have to manually click the Okay button, which seems illogical given that pressing enter works for non-No Split games.

Unless there is a good reason why this behaviour exists? If so what is it

I didnt know that was a thing (mainly playing from mobile), but double clicking to target territory is my way to go in no split (or if I am attacking with all armies in other settings) since it skips clicking okay process.