GTK, QT and the core C stuff make up almost all of the shared library usage. Some obscure png cropping library will basically never end up shared even with dynamic linking. Flatpak does a great job of sharing the 1% that make up the 99% of usages while allowing version locking and bundling of that 1mb binary used by only one program.

Qt in your case is one of the exceptions, just like GTK for Gnome users.

Any application that depends on either of those indirectly depends on libpng and dozens of others. Its a dependency tree, just cutting it of after the first dependency does not make sense in any context and even less so in a context that claims to measure package reuse.

The KDE and GNOME platforms contain all of those indirect packages. They contain basically everything generic that you need to build a GUI app. Then when you go off in to the specific little tools you need, you bundle those in.

Exactly. The situation is the same on Windows and macOS: the platform contains the vast majority of dependencies that might be shared across apps. Beyond that, apps bundle whatever they specifically need.

Oh, I thought that the claim was that there was zero package reuse with linux package managers. Not that there was zero package reuse with flat pack.