Granted, but bash and other readline applications generally have a very different mode of operation compared to a text editor. They operate on single lines of input at a time (most of the time). Editors like emacs operate on a multi-line body of text, and most people expect those to work like the other text fields in their environment (Ctrl-C/X/V for copy/cut/past, Ctrl-A for select all, shift-home/end/arrows to select text etc.)

I know you can activate those keybinding in Emacs, but then none of the documentation you find about keyboard shortcuts will apply to you.

The fact that many places support emacs keybindings (like MATLAB or IntelliJ) are an indication of how many programmers are used to those keybindings, but beginning or aspiring users most certainly are not.

Don't get me wrong. I love Emacs. I use Emacs everywhere, and for everything. But I know that the default behaviour and keybindings were a hurdle to overcome when I first got to know Emacs, and it took me time and effort to get comfortable within the editor.