No, they need a place to live, and it just so happens that the landlords have collectively bought up most of the available housing. It's like saying that a ticket scalper is providing value.
You could literally change my sentence from "they need a place to rent" to "they need a place to live", same thing. You don't need a place to rent if you don't need a place to live :P.
My point is that the landlord is not providing some integral service, but inserting themselves as a middle man in the process to collect money like a ticket scalper.
Given how high rent is getting combined with price deflation from the lack of scalping in this hypothetical, they might realistically be able to swing a mortgage, yeah.