Show don’t tell

I write this on many student papers, but I wonder how many can guess what I mean.  I write “Show don’t tell” when students bury the lead by using unnecessary vague pronouns (sometimes the “lead” or point of which they allude never comes).   I also writers use “some people say” or similar vagaries which hide the agency for ideas, details or facts.

It raises my hackles.  It might be lazy referencing, but it also might be disingenuous.  There may be innocuous explanations, but I need to work on teaching this.