For me, I view Ubuntu as the "higher quality, more mature distro" which I value over "purity".
There is a reason I moved to Debian; it is not like I just like the sound of it better.
My view is based on having used Ubuntu since 2006, Kubuntu since 2023 or so and a serious stint on Debian until they put out a patch via regular updates that bricked my machine's wifi (all of them). So my view is based on real world experience and your comment "Your view does not seem to match reality" doesn't seem to take my experience with Ubuntu and Debian into account.