I think essays are like resumes. I have gotten hundreds of resumes and cover letters over the years - often hundreds for one position. You learn the art of skimming and some are rejected immediately for various reasons, including numerous typos or the cardinal mistake about having the name of the wrong company or position applied for. Others merit a full first read and then others a fuller second read and so on. Essays are no different. Some are sloppily done, others reference the wrong school due to carelessness or it is obvious that it is a cookie cutter one the applicant has done and just hit send for a lot of schools.
My D did get a personalized not from the Admissions Director referencing her essay. She still has it along with her acceptance letter.