No one here saying pets don't belong in the obits is saying it is about comparing level of grief. Sure the grief of losing a pet can be equal or more than losing a human, but that doesn't change the fact that it was a pet who died, not a human. We are comparing human vs. pet, not level of grief.
My pet loses have been the hardest ones I've experienced in my life thus far. That doesn't make them human. I actually consider myself very lucky in that. I haven't lost a parent, a child, a spouse. I have had terrific pets.
Obituaries have a history. Hundreds of years of history. That history is one of eulogizing and notification about the passing of human beings. The fact that I think that should stand doesn't make me somehow unable to understand the grief of losing a pet. There's plenty of room for pet memorials in a newspaper. They just don't belong in the obituary column.
The descendants of my much loved pets will not be researching their lives some day using the obituary column. Former classmates / coworkers / neighbors of my pets won't be notified of their passing through an obituary.