In the corner it can be used in juggles over B23, in fact it's a bit easier to use in the corner then B23, and as for Supermove combos, it is indeed A LOT more convenient then B23. Only in none-Supermove combos mid-screen it shouldn't be used over B23.
Hitboxes and hurtboxes are tied to the model but only in the technical aspect of it as it relates to the size of the of the characters, not the visual aspect of how they look. That is why it is not an aesthetic thing.
And trust me, if I lab for an hour just for ONE hit of ONE string, I would just either ignore that string and go for the other strings or I would just go to a forum, like this, and ask for help, as any beginner should do. And if you are a beginner you would also look for guides on the web, and if you see that the majority don't use a certain string in a a certain scenario there might be reason for it. Not to mention that like I said, you can use that string in juggle combos.
Technically what you said is true, but hitboxes and hurtboxes are go beyond that labeles of attacks. As I showed in a video in another thread, Deadshot's Deadly Assault is a low projectile, yet Sub-Zero can slide under that projectile if the timing is right. As you can see it in the link below:
https://testyourmight.com/threads/sub-zero-can-slide-under-deadshots-deadly-assault-projectile.64949/
The reason for that is that NRS wanted to give Deadshot a low projectile, and it is indeed a low, as if you block it high, you will get hit, but because of the properties of the projectile and the Slide, Sub-Zero can low-profile under it with a Slide while also closing space as the same time.
Are you gonna come and say NRS should "fix" that as well? Or that the Deadshot community should go and do that? The answer is no, since you can't go by the label of the attack type alone. Same thing for the 3,3 string.
I will even go on and say that now that I think of it, I think that considering that Sub-Zero can Slide under Deadshot's Deadly Assault while some (not everyone) can duck under the 2nd of 3,3, that might be self-character counter balancing thing and nothing more.
These aren't "issues", you only calling that because you want NRS to make it easier for you to understand. Of course there are cases that hitboxes and hurtboxes could change, but not every case is an "issue".
No, one of the best thing in NRS/WB games is that they give you the frame data, something that no other company does. It's just that like I said, sometimes the hitboxes and hurtboxes go beyond the attack types.
I will end this argument with this:
Guys you need to calm down, we all need to, Sub-Zero is only out for a few weeks, we aren't sure how strong Sub-Zero can truly be, and once the patch comes out, a lot of characters are gonna be changed and it can change everything including for Sub-Zero, as once the top characters getting nerfed, the lower characters are automatically get buffed. One string that it's hitboxes aren't going one for one with it's attack type isn't gonna kill Sub-Zero, even
@Tom Brady himself said that this might have been intentional from the get go. And who knows? Maybe they will change a couple of things on the last second, as the patch isn't out yet. Hell the list of what they did show isn't fully cleared either.
We need to wait and see what happens, let's all just stop right now and just try to discover more stuff about Sub-Zero. I myself already did that in regards to Sub-Zero's Slide vs. Deadshot's Deadly Assault, you guys can do it to.