Debian, Ubuntu, and Android names are all alphabetical, so you can tell which versions are newer and older. That's all version numbers are really useful for anyways.
Regardless, numbers are easier to work with, easier to remember, and it's immediately apparent what's going on with them. "debootstrap focal target" is more difficult to remember than a hypothetical "debootstrap ubuntu 20.04 target" would be. In practice I have to consult a chart almost every time.