But nobody is talking about any installer.
Say you have a clean Arch install (no desktop environment, just the TTY, installed the Arch WayTM), and you decide to install Budgie. You do it using pacman like this:
sudo pacman -S budgie-desktop
right?
Well, this will automatically also install GNOME on your Arch computer. This is what @fbodymechanic is saying.
The same is true on EndeavourOS, just like on Arch. Exactly the same thing, in fact.