Where are all these small landlords?!

They still exist here and there. Generally speaking, they're cheaper than the big corporate brands but also significantly less responsive because its one guy and his two sons pretending they can handyman their way through a forty unit complex that hasn't had a proper renovation since the 1980s. Because they don't have the state-of-the-art fuck-you-rent-goes-up optimization computers, they get a lot of lower income and longer term tenants. But they're also prime for buy-outs from folks with infinity borrowed-at-0% financing.

So what you'll often see is a large community of people who hate their old small landlord because they have to maintain properties they don't own double-plus hate their new big landlord even harder for jacking up rent to force them out and bulldoze the space.

she was just renting out her basement not hording housing.

Its frustrating, because a lot of this isn't an individualist "hording housing" problem nearly so much as it is an institutional "we only have ranch style housing that sells for $1000/sqft" problem. So while renting your basement is far from the worst landlordism imaginable, it is still functionally profiting from a shortage of housing that your home functionally represents.

Its not her fault. She's just in a position to glean rents off a problem she has no control over, while you are not.

The real problem is for-profit real estate development. Ranch housing is cheap to develop and flip when populations are low-but-growing, while big MFUs cost more up front and clear more slowly. But then ranch home prices inflate as MFUs come into higher demand, and you have an incentive to rent-seek and speculate rather than make way for denser development, because why would you not?