I think a lot of people are saying this about Sekiro specifically because parrying took the place of dodging as the main damage-avoiding mechanic, compared to Souls games. And a lot of people didn't notice it, or insisted in ignoring game mechanics you were specifically told to use by the tutorial. But it's not particularly harder than the Souls games. Honestly, it's their most acessible yet.
Good to know, now it's for sure off my radar. I can never get parrying right, not in any game, not even zelda. I relied on shield and magic in the souls games, timing is not my thing. A larger timing window or clear cues could help, yet apparently having an option like that is an insult to the artistic vision.