So how do you deal with Linux updates? My current Linux install was Fedora 16, but has been rolling upgraded to F25. That's half a decade of updates which include support for the CPU, motherboard and graphics card which all got changed along the way. I expect the machine would run F16, but would be a bit of a dog. It spans changes from init to systemd, from X server to Wayland compositor, the boot loader changed from grub to grub2. These are fundamental architecture changes which make a few Start menu changes look like minor fiddling about.
On top of that, Ubuntu doesn't have the cleanest record on privacy: https://fixubuntu.com/