The vast, vast majority of single family landlords do NOT treat it as a business and don't even properly account for everything; they're being held up by appreciation and if that stops the whole market around that will collapse.
Once you actually treat it like a business, you realize "wow this is why real estate companies don't manage single family homes as rentals" - and if you hire one to manage your property and do the math you're realize you're losing money before appreciation unless you have a small or no loan; and if that's the case you should just sell and buy into an REIT anyway.
I'm not sure I follow you. Most of the houses I've rented were fully paid off so my rent (- minor expenses) was net profit for the landlord. Sometimes it was their sole income stream + retirement. But even if the house is still on a mortgage, and my rent is less than their monthly payment (say 80%), it still means they're buying their house at only 20% of its cost. 40 years later, they can resell and get all of that money back too, even if the house did not appreciate.
Once you actually treat it like a business, you realize "wow this is why real estate companies don't manage single family homes as rentals" - and if you hire one to manage your property and do the math you're realize you're losing money before appreciation unless you have a small or no loan; and if that's the case you should just sell and buy into an REIT anyway.