I've always been wondering why HD is considered a comeback mechanic.
- You don't have to be on the losing side to use it, it's available to both players regardless of health.
- Characters don't get stronger or faster during HD mode and meters start equally empty at round 1.
But here's some of the points that I THINK why people call them comeback mechanic.
1- It can be used to utterly decimate an opponent superior in health with just a hit-confirm. Yes, but then you don't have to be losing to use this. Even though for obvious reasons you don't throw HD when fighting enemies with low health, it is counterproductive, but that doesn't mean you can't.
2- It can be used by anyone who mastered specific inputs and loops to defeat an arguably more skilled opponent. This is perhaps the clinching point, since I've heard people said that some noobs with average knowledge in HD can beat a superior player who knew spacing, footsies, using normals and stuff. Well, I hope nobody take this the wrong way but playing KOF XIII without HD is like playing MVC without the assist or KOF XI without the shift system (or any 3D fighting games without side-stepping or non fg example, playing an FPS without jumping). It's an integral feature that is vital but not necessary in playing the game, nevertheless it is rewarding if one can utilize it. But really, being humans...I believe some if not all of these notions that HD is a comeback feature stemmed from getting one's ass kicked with HD while thinking one is going to win. And one is angry because one does not know/didn't bother brushing up on HD. It is unfair to the game, does it not say that one deserved to win because he used something that although available to you as well, you neglect to use?
In my opinion it is not a comeback mechanic, a comeback mechanic would be something that is only available to the losing side specifically to make a "comeback". HD is more like "damage dealing mechanic" pretty much like supers, since you have to work to fill the bar, and you use it to deal damage and it gives both players equal advantages. After all, won't blowing out EX DM to enemy with high health better that blowing it on low health enemy? then EX DM is a comeback mechanic! or any other DMs for that matter.