I had not – I hadn’t realised that Aperture’s ‘Black point’ slider crushed the shadows like this. I’ve updated the post to at least note that this was the problem, and present a more favourable result from Aperture. Thanks for pointing this out!

Is there a foundational premise or workflow theory backing this behaviour?

I’ve never met this kind of thing in any other image editor, of any kind. I find it very unintuitive, and difficult to use. Granted I’ve only just discovered it, so perhaps it’ll become more intuitive with time, but… it does seem at the very least to make (dramatic) shadow recovery exceedingly fiddly. I tried pulling one slider (e.g. ‘Exposure’) first and then the other, but they counter-act with each other and you get weird results. I found I had to move ‘Exposure’ up only portion at a time, maybe 75% of where I think it needs to go, and then adjust the ‘Black point’ to suit, and then repeat a bunch of times, narrowing in on the final settings. Tedious.

Plus, it just doesn’t match how ‘exposure’ works anywhere else. If I double my actual exposure in-camera, e.g. via aperture or shutter speed adjustment, then it doesn’t arbitrarily keep the blacks pulled down. I guess that’s why it’s so unintuitive to me.

For future reference: the ‘Black point’ seems to ‘override’ all other exposure-related adjustments too, e.g. Levels and Curves.

FWIW I have used the ‘Black point’ slider several times in the past, when I found that it worked well enough to adjust shadows / pseudo-contrast a bit. But even then I’d never realised how it was gatekeeping my shadow detail.