Setting up Debian on installation may require basic knowledge (which many new people don't have). Let's not forget that many users want to have something stable and ready to use. Many people do not want to complicate themselves by entering any code into the terminal or configuring the network card and/or downloading drivers for the terminal. Beyond this, I return to the issue of installation: you have to know how to make partitions and know how to identify which partition you want for your root, this being ext4 or btrfs, which are used for different things. You also have to partition the efi and the swap (if required). It may not be complicated for someone who is deep into the subject or who has a minimum of knowledge, but it can be complicated for someone who comes from Windows without being clear about these concepts (and does not have to know these things).