I find this comparison misleading. When Ubuntu started, Debian was the base. Ubuntu took what Debian made and added polish. Debian still needs a lot of polish

I find this comparison misleading. When Ubuntu started, Debian was the base. Ubuntu took what Debian made and added polish. Debian still needs a lot of polish if used directly to make a distro, many default settings are atrocious. These days, there are many distros using Ubuntu as a solid base and changing the desktop experience. All the official flavours (Kubuntu, Ubuntu MATE, etc) plus unofficial - notably Mint, Pop, and elementary, which get their own category in these graphs instead of adding to Ubuntu's line. If Ubuntu disappeared or never existed, these other distros would also not appear on these charts and things would be very different. All these charts really show is that Ubuntu's own desktop is losing popularity.