A big portion of Capra Demon's difficulty regard the two dogs that are present alongside him. The player is informed how to fight these before, both in isolation, and alongside other enemies, and the strategy holds true in the fight with the Capra Demon, kill them aggressively and quickly. Capra himself doesn't have an especially remarkable fighting style, no tricks, gimmicks or strategies the player hasn't seen before.
I merely said that generally speaking the Souls series is better at teaching the player. More bosses relate to the enemies fort before. For instance I can't think of a single boss that inflicts a status ailment that the player won't have seen before.
Father G fights like a hunter (or you more specifically), a moveset and gameplay style you should be well acquainted with, in that respect the first 2/3rds of the fight are perhaps the fairest in the game. It's a duel with a fellow hunter. His final form attacks like a werewolf (also seen in the preceding level), striking aggressively, with quick, large lunges. Both of these gameplay styles have been already introduced to the player.
Both of the bosses you mention are perhaps within the top five hardest bosses in the game, but at least their gameplay strategies are contextualised appropriately by their environment.
I'm not saying that Souls games are better games (I have not made that decision) however it is clear that more thought goes into how the preceding level implicitly tutorials the player for the challenges ahead. The additional variety makes the levels themselves more interesting, and more challenging too. I don't have to worry about the mistakes I might make in Nioh, how I might missinterpret the enemy and get myself killed, because by and large, I've seen the enemy ahead before.
There's a forbes article about this also. Regarding how the levels themselves are too easy, and the bosses are too hard. Hino Emna is merely the most egregious example of this that occurs in the games first 10 or so hours. But the rest of the game suffers the same issue. Even the following boss, Nue is the same. Her fight doesn't even bare a remote relation to the level preceding it. A level full of Samurai, Ninja and typical Yokai, and then suddenly a lightening dog boss. If it wasn't a simple fight I imagine people would experience similar frustrations, yet it's still a very significant step up compared to the difficulty of the level itself.