Why would rent go down if a large part of the market is owned by a monolith (banks/institutional investors) who can impose price control? This is already slowly

Why would rent go down if a large part of the market is owned by a monolith (banks/institutional investors) who can impose price control? This is already slowly happening. Also the median price of rent in a market is not so much a function of house ticket prices, but rather house affordability. A $400k house in a cash-only market is not more affordable than a $600k house in a market with loans. That is, in a cash market, few people will be able to say ya know, with these rent prices it actually makes more sense to buy than rent - let's go buy a house in full with cash. That all said, I'm not trying to be a lending market lobbyist. I personally avoid borrowing whenever possible, and don't even have a credit card. My contention is simply that current lending practices are the cause a lot of societal issues, but if lending did not exist whatsoever things would be substantially worse.