Thank you for publishing this! I think your general points are valid, but the particular way you phrased this one I don’t agree with.
Most of the time, clarity is important, yes. But if that line was true, fiction writing wouldn’t exist. People love being led astray and then brought back on the right track. All movies and novels do this.
So this somewhat contradicts your next point. I guess you just need to ease up the statement a little.
Also, if all your writing is understandable for fourth graders, there’s a risk that, eventually, only fourth graders will want to read it.
I love this one though: “Give yourself at least twenty-four hours of distance before your final edit.”