I'm not sure I'd want a million versions of every library installed to support both old and new software

While I recognize "a million" was intended to be hyperbole, some could think you're exaggerating from another large number, which is not the case. RatherNott's plan would have two sets of libraries: one from Debian, one from Arch. Maybe three, if you count Bedrock's handful of static executables. That's it.

That's still more than just Arch, admittedly. If Arch gives you everything you want such that you miss absolutely nothing from any other traditional distro, I fully encourage you to stick with it rather than switch to Bedrock. I just want to minimize the chance someone misinterprets Bedrock as some kind of snap/flatpak/etc like solution, which it is very much not.