I don’t understand what problem they are meant to solve. If you have a FOSS piece of software, you can install it via the package manager. Or the store, which is just a frontend for the package manager. I see that they are distribution-independent, but the distro maintainers likely already know what’s compatible and what your system needs to install the software. You enjoy that benefit only through the package manager.
If your distro ships broken software because of dependency problems, you don’t need a tool like Flatpak, you need a new distro.
The Linux purist is to provide the source code and you download then compile the small files.
Developers and gamers don't have storage issues so the higher storage size of flapak and the lack of dependency issues (a copy of every library used) make flatpak user friendly enough for normies aka gamers with steamdecks
Ahhh those were the days:
tar -xzf PACKAGE.tar.gz
cd PACKAGE
./configure
make
su
make install
Not sure many people do that any more. I rather prefer:
sudo apt-get install PACKAGE
Or just pick it from synaptic. If you didn't have to do manual integration, plopping down an AppImage has some attractions too.