If they lose this “right”, they insist on becoming pure profit maximizing machines?
https://www.creditdonkey.com/average-stock-market-return.htm...
However, there's an issue with how you're calculating the market rate: You're assuming that tenants can/will bear that cost indefinitely, so the market rate can be "whatever the landlords want to make it". That won't always be true, not just from landlord defectors who might try to undercut the oligopoly on price, but because the tenants can move elsewhere and effectively remove demand.