This negative sentiment against landlords has always existed. People have to go out and bust their ass for money, while a landlord simply collects money from people to live somewhere. Show me a landlord that works as hard as a barista, construction worker, waiter, etc. A landlord doesn't have to wake up early, stay somewhere for 8 hours a day, commute for 2-3 hours to and from work, and certainly doesn't have to remain busy like a robot. As far as "jobs" go, I imagine being a landlord is one of the easiest. Yeah, you have to evict people sometimes. You might get a bad tenant. Ok, so go to court and remove them. Being a landlord is easy compared to just about every job out there. It's like a nice little white collar job, but with a lot more freedom.
Not to mention because of wealth imbalances, a lot of landlords inherited their rental properties. People don't see it as fair.