I think this can lull people into a false sense of security, and I don't think the author realizes how easy and powerful stylometrics is. E.g. the author says this:

> Spelling/grammar/phrasing > If there are words you often misspell, people can Google it to find other sources where you make the same error (if it's uncommon enough) and potentially identify your other accounts. Use spell checking and maybe Grammarly or similar to minimize this risk, but I tend not to worry about this too much.

It's not just about misspellings, it's that we all basically leave fingerprints in the way we write.