My experience with blades began 25 years ago with a 4 year blade smithing apprenticeship at Iron Wolf Fine Blades under Steven “Bogg” Story which began my lifelong passion for the subject.
The difficulty you have with no brand stainless knives is most likely due to the use a nickle in the alloy. Nickle is gummy, tough, and hard to work with. Drive a nail through a nickle (which is only 25% nickle) and then a quarter to see the difference.
I generally work in tool and bearing steel with the odd exotic so my views on the subject are not clouded by complaints of older alloys but rather direct experience in understanding how the different alloys behave as you change the ratios and amounts of tungsten, vanadium, chromium, et all in the alloy in all states of steel from annealed, to fully hardened, to sub zero quenches and differential tempering techniques.
Yes, you are correct in that the hardness is not the only factor in how easy/difficult it is to sharpen a knife or how quickly it dulls. However, all else being equal (in this case normal standard carbon steel quenched in water to bring to full hardness) the hardness is the most significant factor.
I get that you and many other really like very hard steel blades. But to someone like me, those hard Japanese knives are simply junk when compared to something a good bladesmith will produce.
As for the advertised harness of straight razors, don’t believe the marketing hype. Though I have seen fine example of the straight razor made with fully hardened steel and no temper, most do not fit that description. I’ve probably sharpened hundreds of straight razors for customers and have only held maybe 3 that were fully hard. Most were likely in the mid to upper 50s on the Rw C scale and those 3 that were fully hard were a nightmare to maintain.
edit to add and speaking of marketing hype
Then it is most likely not as hard as advertised otherwise it would be…
