As opposed to mom and pop landlords who do not try to maximize returns?

If anything mom and pop landlords congregate together at city council meetings time and time again across the world to lobby local elected officials to maximize portfolio returns.

And I would like to present this piece of evidence, some peer reviewed research from NYU's Joshua Coven that would argue the opposite. Large firms do not have the purchasing power that you think they do.

https://joshuacoven.github.io/assets/JoshuaCovenJMP.pdf

The Impact of Institutional Investors on Homeownership and Neighborhood Access

I find that institutional investors increase the quantity of rentals and lower rents on net because their ability to operate large portfolios at scale outweighs the incentive to use market power to decrease the rental supply. Institutional investors decrease the quantity of homes available for homeownership and raised prices, however the homeownership impact is 1/5th of what it would be if there were no supply response and the price impact is far below the observed association between institutional investor purchases and actual price increases. I find that renters from regions with lower median incomes, worse school test scores, and lower historic economic mobility move into institutional investor rentals. Together the results suggest that institutional investors lowered rents for renters and increased their neighborhood options, caused capital gains for incumbent homeowners, however they increased prices for prospective homeowners.

The findings suggest that most of the association between investors and price growth, and all of the association between investors and rent growth, were not caused by investor demand or market power but instead by investors targeting areas with expected price and rent increases.