I don't have time ... the volume of messages is too high, and the amount of 'legitimate' inquiries are too low. And the odds of getting ghosted by the recruiter too high.
If they're a recruiter from a company that I know and they WORK FOR that company, I'll respond.
Having said that I think that is a good article and I really like that email.
I know there are two extremes: (a) recruiter is a regular employee of hiring company, vs. (z) recruiter works for an unaffiliated placement company.
But i.e. if a recruiter is a temporary contractor with the hiring company, they'd still have an email address from that company, right?
To some extent a contractor who working for the company I know ... I'd still consider that a direct company reaching out to me type situation that I'd be more inclined to respond.
I don't find that it is hidden all that often, but that's just my experience.
I see plenty of recruiters who just work for recruiting firms and don't hide that fact. Anyone who won't immediately tell me who they're recruiting for gets ignored. I'm sure I end up talking to the occasional contractor but you can easily filter out a lot of obvious low-hanging (and rotten) fruit).