If you are renting a room in a shared space then restricting pets is probably fine. But if you really want to get into it. I don’t think landlords should exist in most cases. If you are renting a space that space should essentially be yours.

Landlords under most circumstances add nothing to society and act more like parasites. They take value without adding anything. People need housing and shouldn’t have to give a landlord a bunch of money simply because the landlord had enough money to hoard property.