Why Debian?

Debian is the "grand daddy" of many common Linux distributions today. Its age implies a long time of development, understanding, and implementation.
It's extremely easy to install and use. Time is valuable and can easily be wasted setting up and configuring other options. Debian includes the apt package manager, making the installation of key software a one or two liner.
It's not Ubuntu. Ubuntu is moving away from APT in favor of Canonical's own Snap, which creates a division in package maintenance efforts as well as unnecessary confusion for the end user when looking for where to source new software.
It's dangerous. Debian does not stop you from using the root user, unlike some distributions. If you wish to spin up a single user server environment and execute everything as root, you can. There's no need to ask for permission to do things on your own server or virtual machine.