There are probably easy loopholes to get around your suggestion. Just form another LLC and purchase the property under that LLC instead of you as an individual, then each entity owns only one property, so they get the standard tax rate instead of what you are proposing.
Of course this would be a giant pain of a workaround to scale, but for the non-mega corporations it'd probably work. I'm sure that the huge corporations owning large swaths of residential properties would figure out scaleable loopholes.
Just tie the "first home" tax exemption back to a person by making business entities a pass-through to the registered agent (or some other single officer). i.e., an LLC can't claim the exemption, but the agent can pass their exemption through the LLC to a property.
Of course this would be a giant pain of a workaround to scale, but for the non-mega corporations it'd probably work. I'm sure that the huge corporations owning large swaths of residential properties would figure out scaleable loopholes.