It's not so much about any longstanding personal policy, but if your dog of 10+ years had just died recently, and you sat down to watch a movie to relax, you might not want the movie to feature a prominent animal death, for example.
You will either way. Attention and time are finite, media is effectively not. There's no inbox zero for movies.
This DTDD website is for people who will definitely not enjoy the film because the dog dies. Many of these films are quite lazy anyway - the dog is just a plot device and they kill it as a cheap way to build up tension. Basically you won't miss much from skipping them.