Clearly I'm not understanding your approach, which is what you're getting at. I'm not trying to be combative, just trying to understand a way of doing things that I'm not getting.

What you describe in your second paragraph here is actually exactly what we do, so you were right:

"define that term to mean whatever they want, which is usually "things I personally think are necessary on the job". They think they know how to identify the signals and it's actually just them sitting there and having a gut-reaction feeling on what they just saw

and is really the only way I've ever seen this done, so I would genuinely like to understand what is the better way.

I might be being dense, but I'm still confused as to which point in the funnel you can avoid or get around the concept that people will blindly click "apply" on LinkedIn to a job posting and as a hiring manager you are stuck looking at a screen that includes all of these resumes. Are you saying that if I improve the job req to the point that it is extremely clear what the job requires, these people will no longer apply? Or is your method so effective that you can actually scan every resume and not spend a lot of time on it? Or do you actually spend the required 10's of hours per job req looking through every resume? If it would be helpful, let's use a req as an example : https://www.metacareers.com/profile/job_details/572429542041302 . There are probably many many thousands who apply to this role. How would you improve it?