I don't think any one believes you and you are deluded.
Sekiro is easily the hardest Soulsborne game and it's no contest.
I am not sure on what you don't believe me. But since you refers to difficulty after I might need to clarify some things.
You say Sekiro is hardest than Soulsborne (I don't include it into the "genre" because it's a not one of them for me) and
I fully agree with you. This game is much more difficult and demanding than any Soulsborne. You have to know pretty well the bosses moveset and reaction to beat them. You can not easily "improvised" something during the fights like in Soulsborne.
I might have made it sounds like the game was easy because of my
You can basically L1/R1 almost every boss.
You can beat most of the boss with mainly L1 and R1, especially the most iconic of the game (Genichiro and the final boss for example). BUT it's not easy ! You have to know the timing (which vary for each attack) to deflect and not mash mindlessly the button. Yes there is the perilous attacks, here and there, which you have to counter by jumping/dogding/mikiri. But other than that, I find the L1/R1 being really efficient and much safer than to experiment with prosthetics.
That being said, I am a lover for Prosthetics tools and Combats arts, and use them extensively during battle (I have no emblems left after each battle) mainly to bring diversity and "style" to the combat. I don't look efficiency, I look for pleasure while fighting.
I guess this statement is also a problem :
But still in the back of my head I always have the feeling I put myself a handicap by using them. I could just L1 and be more safe and efficient.
So let me explain with some examples.
I am huge fan of the Raven mist. I use it for style reason. But each time I use it, I just think "I could just deflect this attack instead of using the Raven". The plus is that, in most of the case, it guarantees one R1 (with the dash follow up) for vitality damage but vitality damage is not the priority in Sekiro. I can also reverse lighting without cheap damage but you can just do it by Jump + L1 (at the cost of really low cheap damage) so again if I was looking for efficiency, I would probably not use it.
I really like using the Sabimaru. But it takes a lot of emblems and time to poison some bosses and you have to really pay attention to dodge incoming attacks with R1 mid combo. And it does barely no posture damage. But if you succeed to poison, it guarantees a lot of vitality damage. But it's quite costly in emblems and risky to use.
Also the Axe, really slow but decent posture and vitality damage IF it connects. And to find opportunity to land it without having to tank a hit (because in NG+2, no charm and demon bell you don't want to take a hit) is not easy. Again each time I am like "I am stupid, I could just R1 here instead of using the Axe".
And this can be said for most of the tools.
But still I love using all of them.
Of course there are (designed) situation where prosthetics will greatly help you. Like the firecrackers on animals, the flame vent and spear on the Guardian Ape, the Sabimaru on O'rin...
There are these situations where the game WANTS YOU to use a specific tool to make your life easier. But it's too "scripted" and situational for me.
Hope it clarifies my view. I had similar discussion with a friend who thinks prothestics are huge tide changer and don't get me when I say that L1 is too powerful and can replace almost all the Prosthetics.
So I know this is mostly a really subjective topic (I have another friend playing the game now, and he's more on my side : he doesn't see the point of using Prosthetics instead of L1 in most situation)