Why can I only take notes with the apple pencil and not with the keyboard?

Why can I only take notes with the apple pencil and not with the keyboard?

You can choose between handwritten notes using the Apple Pencil and text notes using the keyboard only in the native iPad App. To take notes using the Apple Pencil (or finger), select the "Pencil" option at the bottom of the notes page. To make text notes, select "Keyboard". 

In the browser-based observer interface only text notes can be made using the keyboard.

You can learn more about the notes here.