Snap makes a lot of sense for desktop apps in my opinion. There’s a conceptual difference between system level packages that you install using something like APT, and applications. Applications should be managed at the user layer while the base system should provide all the common libraries and APIs.
It’s also worth noting that this is a similar approach to what MacOS has been doing for ages with .app bundles where any shared libraries and assets are packaged together in the app folder. The approach addresses a lot of the issues you see with shared libraries such as having two different apps that want different versions of a particular library.
The trade off is that you end up using a bit more disk space and memory, but it’s so negligible that the benefits of having apps being self-contained far outweigh these downsides.
The problem here is that for that purpose, Flatpak is better in nearly every way and is far more universal
I think Snap makes the most sense for something like Ubuntu Core, where it has the unique benefit of being able to provide lower level system components (as opposed to Flatpak which is more or less just for desktop GUI apps), but it doesn’t make sense for much else over other existing solutions
