You’d have to die a few times to it too even notice it getting easier. Almost nobody wants to grind out a boss 20 times in order to beat it. And if properly done, the variables changed are so small each time, that it’s not noticeable.
It’s a system to help everyone enjoy the game without quitting out of frustration. Because the majority of people, in general, quit after a bit too much resistance.
There’s a quick drop off of enjoyment when a player feels the game is too difficult.