"The guide carries plenty of evidence of a long debate about what words can be both noun and verb: “login” is a noun, with “sign in” given as the preferred"
That's because the real verb would be "log in". "login" is just a convenient verbified term, but confusing to non geeks.
So they don't like hyphens? I think they should be used more in the English language to avoid confusion, and reflect better the nuances of the actual spoken language. In many languages words are just concatenated without the hyphen.