I think its a step backwards, as you loose tight control over dependencies. E.g., in case of a security issue, one cannot easily patch all containers if they are blackboxes.
IMHO, the right tool for this is an improved package manager such as Nix or Guix (which incidentally also support containers in their own way). Perhaps the future should be a Nix-like package manager for dependency management, and container-ization for security and resource limits.
Containers fix a problem that unix has solved for decades.
https://en.wikipedia.org/wiki/Soname
The problem is the package managers used by most distros getting hung up on there only being a single version number of each package name installed at any one time.
Sort that out, like say how Gobolinux does it, and you do not need containers.
But containers is all the rage on the web these days, so ipso facto is also must be all the rage for desktop Linux.
Back before Gnome and Freedesktop, desktop Linux was a kernel up project. But more and more these days however it is a web down.
Meaning that web people get interested in using the L in LAMP on their desktops, start looking into Gnome/KDE, then get involved in Freedesktop plumbing, and all the while bring their web-isms ("move fast and break stuff" being the most annoying) with them further down the stack.
We supposedly discovered concrete 2 millennia ago but only adopted it widely 150 years ago.
I wouldn't diss people who actually have a shot at fixing the problem, even though you might not like their solution.
I use debian all the time, and the major libraries are versioned, and some have more than one version available. Debian is a very common linux distro, and through it, a lot of child distros get it too. AFAIK, RedHat and Fedora do this too.
So, do you mean that the state of adoption is bad for niche linux distros?
I've never actually used it, though, since Debian packages work fine for me.
It might sound crazy when you consider some of the services typically installed with a package manager but ultimately there's no reason why an "app" cannot run in root, many root packages aren't actually installing drivers, they're only root for historical reasons (e.g. being able to read/write to /etc).
Why, for example, couldn't a web server be an app? Or a DNS client? Or a DNS server? Sure, there are certain system services which cannot (anything installing drivers/filter drivers/core UI/sound subsystem/graphics subsystem) but MOST things can.