As someone who lives in a rental, and who also has a home that I rent out as a landlord, I think this is silly.
There are plenty of reasons people want to live in a rental rather than buy a place. How is it unethical that someone meets that need? Even if somehow fewer people owning and offering rentals drove down buying prices, it would also drive up rental prices. How is that better? I would certainly be worse off in that scenario.
The place we own is currently rented by three roommates. So presumably, being forced into buying wouldn't be practical or helpful for them. It would likely make their lives far more expensive. (BTW, these are three working professionals, not college aged. They have very solid credit and income, so presumably renting with friends is a conscious choice they are making because it best suits their lifestyles, whether that's financial, social, shared housework, or something else.)
Also, this is a very HCOL city (SoCAL) with significant housing issues.
We move every few years (military family) and have no desire to buy on that timeline, especially when we have no say in when we move so we could easily end up needing to sell in a very terrible market. Our current location is also in a also a VHCOL area with significant housing issues. I'm thankful to have a rental.
I'm not sure how providing a service I want and need, and sparing me having to buy and sell every few years, is in any way "unethical". Weird. The entire concept seems sort of myopic, as though what is right and best for one person is right and best for everyone and should be encouraged. If it is best for *me* to own, then we need to make it easier/cheaper/faster/better for everyone to own, even if it makes the alternative more difficult. And that's nonsensical and seems to lack a certain wider world-view.
It's unethical to treat your tenants badly, to not keep the house up to decent standards, to try to keep as much of their security deposit as possible. But to offer a service/product for which there is high demand? I don't see how that is unethical.