I don't think something that requires high skill input and timing is "game breaking".
It is when it trivializes the whole game.
For example, in the original OG Xbox release of Ninja Gaiden, the flying swallow move was so ridiculously effective that they actually had to "fix" it in the later re-releases and the sequels.
The same thing basically happened here with Low Ki Dodging. It was just too damn effective even at low level play. The low stance often ended up being a much greater force to be reckoned with as a result.
Edit: In response to your edited post, DMC is intentionally designed to be a combo happy game. Nioh was not. The fact that you could do Super Slick Stylish combos in the Alpha was a complete accident on their part. This is why the stam system exists in the first place. To stop you from doing that.