The software philosophy of the maintainers and their choice of packages and design.
A simple but important difference: the package-manager: apt, dnf or pacman (there is more but let's bring it down to these three).
Another one is security: apparmor or selinux
The last one are preferred and preinstalled Desktop-Environments.
And if you want to keep it simple, just be based on another distro and let them do the hard work.
Everyone can start their own distro. Manage some packages together, choose for example: Based on Arch, pacman, selinux and hyprland-wm and name it hypearch. Et voila!
But isn't appimage the closest one to the app-system from Android? Since things could be really different on many clients an "app-container" is the best solution.
Why not containerise everything? You need libreoffice? No problem, here is a docker or podman container.
BTW. I like flatpak, too. It's the most stable, but I never understand it's mechanics. There is always another pack installed, freecode, gtk, qt whatever. Even if the system has already the correct gtk version, nope, the dev decided to use the gtk image from Ubuntu.
Just read the comments, and have to add, don't forget the mastermind behind his speeches. Goebbels. Hitler's performance is for a native speaker of today a bit of too much anger, loud, and a rolling "r" nobody actually speaking in germany. It's like a special Hitler-accent, if someone tries to speak like that, everyone know it's about making a Hitler-Joke.
I could follow it a bit. CalDAV is mostly nerd stuff. And proprietary apps use to disallow CalDav to sell their own stuff. Best example: M$ Outlook doesn't support CalDAV natively. You can only add them as only read, or use third party addons. And why? Because they want you to buy 365.
Look at it as the average Bob: wow you can sync all your contacts and Calenders and Tasks to every device? That must be expensive!
Handedness has some "connections" to the use of the brain sides. One side is better for doing math and I suppose its not the one mostly used by left-handed people.
The struggle for left-handed people like me is that you always meet tools made for right-handed people. So you have to use the right hand more like right-handed the left. This makes left-handed people more ambidextrous. Scissors are always in my right hand. As a kid I tried to learn writing with both hands at the same time, worst idea ever but it works a little bit.
Btw. Mental arithmetic is the endboss for left-handed. So don't say left-handed are more successful.
Thx