sure, arch is cool, but can it be considered the fast version of LFS? Stupid question, i know.
It's not clear to me that it's a stupid question at all, but rather raises the issue of versions of linux.
Whilst it's superficially the case that all linux distros use a linux kernel, and most use GNU software, that notion actually obscures the very real differences.
The notion that any linux distro can be constructed to have the same functions as any other distro, may be technically the case, but in the real world of computing, it's very often not a trivial matter to do that, which is the basic reason so many specialised linux distros exists.
To build a basic linux installation and then install the functionality of a specialised distro, doesn't just involve installaton of a bunch of specialised applications, but will often involve the need to compile a new linux kernel as well, sort out dependencies and conflicts, and ensure functionality. Developers of specialised linuxes usually issue kernels which deviate significantly from the vanilla kernel.org kernel so that their kernels are optimised for their speciality.
Here are some examples of specialised linux distros:
Alpine linux: a very small distro with no GNU utilities by default and suitable for embedded environments. It uses busybox utilities.
Academix: a distro specialised for education and for the installation of educational apps in maths, and sciences.
AV Linux: a distro specialised in video and audio production software.
Apodio: a distro specialising in music production and editing.
wattOS: a distro specialised for low energy consumption and efficient energy use.
Here is a more comprehensive look at specialised distros:
Here is the complete list of all Linux distributions that are developed for special purpose. If you are a fan Linux operating system, you need to review and bookmark this page as you will need it in your future Linux projects.
www.coding-bootcamps.com
Often specialised distros are small operations, sometimes very small communities and sometimes even a single person. That is however, no reflection on their usefulness. There's more nuance in the area of specialised linux and of linux in general than the broad brush statements provide.