I can write an editor using tools others have built, too:

  apt install emacs

Or should we, perhaps, consider “from the ground up” and “from scratch” to mean something?

Your argument is reductio ad absurdum.

My argument is that words have meaning.

And my argument is that meanings are fluid and "from scratch" is something a reasonable programmer should understand in this context.

For example, for me someone writing a new editor not using advanced components such as existing programming editor components counts as "from scratch".

They don't need to use magnetic needles to shift individual bits on HDDs.