I don't know if there are automated filtering systems that will send a rejection email in place but I know as a manager who used LinkedIn job posts I had what was basically a, "qualified" and then a "not qualified/spam" folder for applications. New applications were auto sorted into one or the other depending on their resume/linkedin profile/some other factors I was not aware of.

I could still find those profiles but it was auto filtering the candidates it thought were relevant and those that were not. To at least some extend these types of automated filtering systems do exists. I don't know why recruiters/manager say they do not.