You can't even be sure a cover letter is read. Sometimes they are, sometimes they are skipped. When I have 100 applicants I don't have time to read cover letters, I'm looking for the first bullet that suggests you can do the job otherwise I'm trashing your application (The goal is to get down to 10-20 resumes that I then spend a minute on to see if you go into the interview or not pile). I'm only going to read that cover letter if something suggests you despite lack of the experience I'm looking for you might have a different background and so be worth hiring anyway.

Remember I have lots of more interesting things to do than read your application. When we are hiring (like many we are not today) I take time to do the process, but I really want to be doing the more interesting work.