Since thie tutorial aims at absolute beginners, the author chose a beginner-friendly distro - Ubuntu LTS to be precise - as starting point.
Unlike many other distros, Ubuntu is quite beginner-friendly from it's UI, UX and community and thus is an ideal starting point to begin with. Furthermore it comes with most drivers out of the box and requires very little hands-on to get setup. A lot of the steps taught may also apply to it's upstream distro - [Debian] - and subsequent downstream distros - like [Pop_OS!].
Of course nothing prevents one from going hardcore mode on [ArchLinux] or even [Gentoo] but if you do that you should already be familiar with Linux and it's CLI tools and then you're propably not the target audience for this tutorial anyway!
So please keep that in mind...
If for whatever reason you're stuck with a low-end system too slow for Ubuntu LTS, [RaspberryPi OS] and espechally [BunsenLabs Linux] may be viable alternatives.
Since we don't go too much into distro-specific details, you should be able to apply most of it 1:1