I'm not familiar with how For Honor works (past that beta test from a few months back), but why didn't they simply ban this exploit if they thought of it as such? In fighting games it is common to run into unintended mechanics that either improve the viability of certain characters (while not making them broken) or outright turn them into a broken mess, sometimes people just roll with said unintended mechanics because they're reasonable and offer more variety in gameplay. I don't know how broken this exploit is in For Honor, but I'd guess more people were using it in the tournament, only that the winner was more efficient at it and won.
DHC Glitch in MvC3 was an interesting case, I liked it, but it ultimately didn't help the weaker characters since it was mostly the already good ones who had it like Dante, Zero, Wolverine and Magneto, they certainly didn't need even more tools lol. There were also minor ones like Cody, Ryu and Gen (?) in SF4 who were able to pass through certain characters after hitting a normal and immediately FADCing, those could serve as some kind of mixup, which I believe is fine. There was a timer glitch in MvC3 I believe, which would make the opponent's character never come out after a snapback and there was also one with Thor which outright locked your character in place, those are examples or actual broken exploits.
Edit: Dunno what my stance is regarding the infinite TAC glitch though... shit isn't that easy to pull off and you need lots of practice to get the timing down consistently. Makes for really boring matches when someone does it against you though lol, Zero loops are already boring af and they're completely intended.
