I'm used to writing with ~3-8 different colours. My colleagues are amazed (and make a bit of fun) that when I lend them an essay, every colour has a meaning. I also use block letters and cursive to subtly alter the meaning of a phrase.
I've done this since highschool, because a full page with single coloured text seems incredibly boring to me, and it draws my attention away.
That sounds incredibly difficult to read for most people. How sure are you that it's an effective method to communicate with other people? (Or is it just something you do for your own stuff, and other people get plain text?)
It's an effective method to write for myself, most of this stuff is meant as drafts that only I (or few people) are meant to read.
But it still sounds worse than it actually is, I promise it's a lot clearer than it sounds. Most of this is technical stuff with formulas or code, so it helps a lot more than it seems from the description. And the "full 8 colours" are only used in special cases with a lot going around.
I've done this since highschool, because a full page with single coloured text seems incredibly boring to me, and it draws my attention away.