because Notes is not a text editor.

I can open TextEdit and immediately start typing within a few milliseconds. Notes opens the last note used and takes a few seconds to load. Then I have to manually create a new blank note. Also, I have to remember to delete the note when done because they're saved automatically. When I'm done with TextEdit I can easily choose not to save the file. Using TextEdit is more of a seamless process and doesn't clutter up my files while also using less screen space.