I assume that nobody would use installers from an unknown source. What benefit do you see in creating a custom iso over just customzinig after install (possibly scripted)?
My use case was to create a bootable Live USB with some software already preinstalled, which people can try in a course, without having to install anything on their computer. While for long-term courses, students can prepare and install everything, I am also offering such a course in a conference, where people are most likely just going to pop-up into the room.
Maintained and works like a charm in 2023 (e.g., for Ubuntu 22.04), the documentation and interface is great, the maintainer is very responsive and helpful.