I was thinking about why a small landlord might be better, and I know there are exceptions, but usually a small landlord is is not going to squeeze every penny out of their rentals, sometimes out of the goodness of their heart, but most importantly, a small landlord has other ways to be productive.
A small landlord who has a normal job, if they want to improve the world, they do it through their job or personal projects, they build something or create something or whatever.
A big landlord who does nothing else, they aren't actually creating anything, they're just rent seeking and the most creative way they can imagine to improve the world is to rent seek even harder.
Our economic system gives greater rewards to those who move money around than to those who create things or cure cancer or anything else. The ways of turning a lot of money into even more money are taxed less (usually not at all) than more common ways of earning money like working a job or creating physical goods. The richest people didn't get rich by creating something that improves everyone's lives, they got rich by moving money around.