[tremon]

So, Flatpak and Snap solve the problem of wanting to run stale software? That ought to be a very niche requirement, I would think.

I was under the impression that Debian already solved that problem by allowing you to deploy an older Debian version in a chroot with debootstrap? As long as the Linux kernel is binary compatible, that should work fine. Although I have to admit I don't use stale software that often, so I have little experience in that area.

[zorr]

They solve the problem of being able to run software against a known set of dependencies instead of depending on the versions that come with the distro. Older packages can still run even when the dependency version the distro provides has changed in a breaking way (as parent suggests), but also the other way, new packages can ship features using newer dependency versions that the distro might not have yet.