We're talking about landlording, not what they did to afford to start landlording.
They didn't make the building and, while they put down the first payments, their tennants are the ones paying for it.
That's not creating wealth. That's not work. That's living off the wealth created by others.
If it's so easy to own a house, go buy one
Like all other passive income, the challenge is having enough money to start with.
Once you get past that point, it IS easy, but due to the inherent inequities of capitalism, getting there is literally impossible for the vast majority of people.