Why a zoo of distributions with different features?

[Firestorm]

Additionally, it's a bit of alchemy to find out which driver version (the hacked ones from RockChip, Broadcom or whoever, or the open source version in the mainline kernel) work with what version of the (often closed source blobs) of the firmware(s).

And that, kids, is the reason why general purpose ARM device just don't get off the ground: licencees of ARM cores make their chip, hack a specific x.y.z-whatever ancient linux kernel version and sell it as an "appliance". Source sometimes gets released if someone asks, but almost never updated to newer kernel versions, or even with a non-heavily-patched-hacked-and-broken version x.y.z  

It's the same for android smartphones, "NAS"-Appliances, and for all "RPI"-Replacement boards.

That is an interesting insight, thanks :-)

I believe I have read there was also some difference in terms of HW support between the two distros offered by the community which do use the same kernel (debian and ubuntu) -- which was the origin of my question -- but now I cannot find that post anymore