Yes, landlords do the things they do because of capitalism. Their existence is due to capitalism. But that doesn’t mean they’re not to blame. They choose to be landlords.
Your anecdotal experience of nice landlords doesn’t cover the fact that landlords, traditionally, have been bastards to their tenants. There’s a reason many countries have had to implement laws like third party deposit schemes and standards for things like smoke alarms, heating systems, etc in rented accommodation.
Landlords are bastards because of capitalism but that doesn’t wash away the fact that landlords are bastards.
Hoarding living accommodation for the purpose of profit.
Landlording for an office or shop could perhaps be justified to be for-profit but housing is a human requirement and hoarding it for-profit is unethical. All landlords are bastards, unless by some unlikely chance they’re running their business as a nonprofit.