Diplomacy is generally ineffective in combat and against creatures that intend to harm you or your allies in the immediate future.
“Generally” means usually, commonly or ordinarily.
But still there is a chance to change someone's attitude by 1 or 2 steps from hostile to unfriendly or indifferent.
“Hostile” means aggresive or antagonistic.
Using Diplomacy to influence a creature’s attitude takes 1 minute of continuous interaction.
Combat is resolved on a round-by-round basis.
How is it possible to change someone's attitude from hostile to unfriendly, when there is no time to do that? Does hostile mean always combative?