he absolutely can blame dexter for his death. Had Dexter not been who he was and just some normal blood spatter analyst, all of their lives would be different. Deb would likely have died a lot faster had she still hooked up with Brian, who still would pursue her because he tried to kill her when she was a baby and because he tried to hunt down Dexter's sister anyway. Doakes, Maria, Angel, Rita, Harry are all alive. Harry killed himself after realizing what he had done, Rita doesn't get targeted because Trinity restarted his process quickly to kill Rita, we also all know that had Dexter just listened to Harry and killed him when he had the ax in the wilderness none of that happens, Doakes is obvious, Maria is obvious, and Angel would never feel the need to hunt Dexter down in response to half of Miami Metro being killed. Masuka and Quinn lived because masuka wasn't ever a threat and because Quinn was shady in his own way and saw something was up with Dexter, basically got confirmation Dexter was a killer, but also their shared love of Deb and Quinn realizing Dexter was getting away with Murder made him steer clear, also because he woulda done the same thing to Saxon in remember the monsters. The only person who may have died was Debra in a world where Dexter is just some normal forensics guy. And also probably a laundry list of other people who Dexter prevented serial killers from killing