Many FromSoft fans would not agree that this is what the gameplay is about. They’ve always put easy modes into their games, but the game designers really want you to just keep practicing until you get it.
Many of the boss encounters they’ve designed are also specifically about fast reaction times and precise timing of the controls. In the souls games recognising the enemies patterns are reacting quickly with precisely timed attacks and rolls is very important. In Sekiro the entire game is about precisely reacting to fast paced combat, especially if you’ve got chip damage enabled.
To say the games are mechanically easy just seems like such a nonsensical take to me. Simple perhaps, but lots of simple things are especially difficult.
You make souls games out to be "memorize the trick" simulators. No, no, no. That's the unfun approach.
While the strategy could be oversimplified to 'hit hit run', it misses the nuance of learning how to apply that strategy to a given boss. I ended up clocking over 600 hours on DS3, between personal challenge runs and invasions, and as the other comment suggests, your level (and gear, and how you distributed your stats) will have a big impact on how difficult a boss feels.
My first playthrough was an absolute slog, since I had very little idea what I was doing with combat, and had no idea how to optimize my character. On my 20th (or whatever) time, with a purposefully under-leveled character (Strength build), most bosses were one-and-done with the right game-sense and cheese tactics (Greatclub is great, and if you disagree, you are liable to be flattened).
If I'm in the zone, Gundyr is a minor roadblock between character creation and Firelink shrine. I think my record is around 2 minutes to activate the shrine bonfire?
Vordt? Gimmie that raw +3 (I think) broadsword with lighting resin, and he's dead meat at SL1[0] since his timings are very predictable after the 15th time killing him. Getting a raw +3 broadsword is the hardest part there.
Dancer, Pontiff, and the wrinkly pink screeching guy in the castle side area are still my hardest fights due to their patterns and movesets.
[0] SL1 = Soul Level 1, achievable when you start as the naked guy with a club and never level up. All other base classes have a starting SL greater than 1.
At first the game will show you an enemy with his back turned, and you will discover that this initiates a devastating backstab.
Miyazaki has shown you a new tool, but in doing so has also given himself a new tool for manipulating you: A few moments later, the game will show you an enemy with his back turned, and you'll probably mindlessly rush in for the rewarding backstab, only to be bum rushed by an enemy hidden behind a corner that kicks you off the cliff. You really don't stand a chance at reacting to this, and yet again meet see the familiar "You Died"-screen.
This is the dialogue I speak of, it's easier to point out in level design but very much also exists with in the combat system. Some players will probably miss this aspect and think it's just cruelty. Like, how could you have known? Well you absolutely could have known by being being more careful and looking around that corner before taking the bait.
The combat in general works like that as well. First you're shown enemies that are susceptible to one particular strategy, and then the next, you're shown enemies that are not. The difficulty isn't executing, but coming up with an appropriate strategy for the situation. And the games are very cleverly designed to shut down one-size-fits-all approaches to combat. There are no universal combos to memorize because they don't want you to merely go through the same motions, they want you to engage with what is happening on a more direct level.