Actually, I think the problem isn't the HP drain, its that successful hits give more of a boost (specifically spinners and sliders)
I'll see if I can find actual proof, I just noticed it when I watched my replay of my best play of
The Office Theme (Dwight's Challenge) and I distinctly remember almost failing in the last few seconds, but the replay shows me having a fair amount of HP.
EDIT: OK, I just opened
Boten Anna (Insane) in the editor, and you will notice this slider 00:57:77 (6) will drain your HP when you are playing, but the HP will remain stable when it's on Autoplay (it's the same for all the sliders, it's just easier to notice on this one)
It's not a replay, but maybe this has something to do with "the computer" playing in general?