We need the ability to create notes and keep it within the page margins, so that we can design for print out.
The vast majority of notes that are created, never need to be printed, but if you wanted to create a note that was to be printed, then you would want the ability to create the note within fixed margins while designing.
Example..
If I create a table to show expenses and need that printed as a handout, it might look great in the app or on the web page, but when you go print nothing works, your table is chopped up into several pages, the top row of the table does not line up with the rest of the columns, etc. But, if you could know the limits of the printed margin in the design of the note, then you could plan around that and make sure it prints as it should.