I concur. For me, it's the concept of diminishing returns. If you kill off my favorite character, then you're going to kill of my next favorite character, yada yada yada. My interest in your show is directly proportional to your interest in keeping characters alive. Usually it takes more than one character dying to get me to swear off a show. (I'm looking at you, Stupidnatural and The Nagging Negan, ER The Walking Dead.)
Now it just takes one favorite character to kill my interest in a show.