You are forgetting the 80s had atmospheric horror and so forth also...Not just slasher films. The Shining, The Thing, Poltergeist, and The Changeling are a few good examples. Just like today it all depends on the type of horror film you are watching. A splatter film is a splatter film regardless of when it was made...although some of the more recent entries to the genre out of Japan are definitely on a whole different level compared to classic splatter films. Like Tokyo Gore Police for example.