Yes, I agree, we come close to developing all the shadow detail in a normally exposed negative. No argument there. "Pushing" film by underexposing a "normal" negative will give you empty shadows. It's just plain underexposed, and there's no magic potion that will fix that - all you can do is salvage as much information as you can.
Originally Posted by ntenny
Two trains of thought here: First, if you rate film at a higher EI in flat lighting conditions, you're going to retain more shadow detail. The subject brightness range is lower. You can make the negative appear a little more normal by increasing development. In normal or high contrast situations, you're going to lose shadow detail and there's no way back. Using something like Diafine compensates for pushing film by keeping the highlights from overdeveloping while the shadows get as much development as they'll ever get. You're manipulating the film curve, and it's a compromise.
I stopped pushing film about the time TMZ showed up on the market. It outperformed pushed Tri-X so well I just never looked back. Now that I no longer do much 35mm photography at all, I handle contrast differently. I also find myself contracting tonal ranges a heck of a lot more than expanding them, and divided Pyrocat HD or reduced agitation schemes in Pyrocat HD gives me great results. If I need some punch, I'll rate the film slightly lower and increase development or switch to a contrastier film like Ilford PanF+.
The OP was asking about using a developer that wouldn't help much at all. HC-110 and Rodinal are not the best for retaining shadow detail in a push-process situation. X-tol, T-Max developer, Acufine, Diafine, some of the Ilford developers will do a better job.