There are still some reason that you may want to use a newer version of a software when your distro is stable. e.g. The latest version added a new feature that is really useful to you, or a long-standing bug has been fixed in latest version.

I think Flatpak would be current best choice for these tasks if you are running a stable distro. But I think it would be good to have a distro where core OS and user application is completely separated, and can be updated independently. It would be nice to have latest application without fearing the next grub/DE/kernel/driver/... update might break your current setup.