Why does it matter? A little lost HP never killed anyone.

I mean, seeing some of the beatdowns he got in this season...

Beatdowns that were meaningless since he can just use full recovery afterward.

Provided he survives and he sometimes has to use them up...not that doesn't he finds ways around it, but I don't think it makes all his fights meaningless depending on the actual fight itself.

He will survive. That's not even a question. There's always some deus ex machina ready to bail him out. Either that or he just pulls a stunt that he could have pulled off at any time but decided to wait for whatever reason.

I feel like most of the "deus ex machina's" are his own willpower and strength or a function of the system that had previously been established.

Being sent to the penalty zone? Having access to a shop that sells game breaking items? Being able to level up? Tearing a snake apart with his bare hands? Stabbing a guy in the eye?

I'm sorry, but none of these shout "willpower" to me.

I think the bolded are definitely "willpower" thing (unless you're talking about how he got strong enough to do that but that's because of his training and stats).

And at least the penalty zone and the shop were established beforehand.

That snake thing reminds me that in the first Kingdom Hearts you could instantly grow experience by blocking a special move from the enemy similar to parry.

He didn't gain experience though. That wasn't some kind of special move. He just literally tore off the snake's skin.