>Far too much of Ableton's secret sauce is hidden away behind Max for Live
The other way around. Ableton exposes some internal modules to Max for Live as Max for Live modules.
What Ableton gets from Max for Live is not internals, but basically a few Ableton-only Max-built plugins, that could as well use VST underneath.
I answered this in a different branch of the thread, but you're kind of missing my point. I don't own Max for Live, so the large ecosystem of useful tools that I'd enjoy trying out is unavailable to me.
It's not about special powers, just being forced to pay the gatekeeper to the otherwise free/OSS ecosystem.