There are situations where it makes a lot of sense - for example, we just visited family where it made sense for my sister and I to share AirBnB houses since there were 3 young children and having a kitchen and separate play space was important. The problem is a lot of people got into real estate speculation thinking it’d be free money and they didn’t spend enough time thinking about what they were giving you over a hotel room.

> real estate speculation

I suspect many wanted an arm's length almost passive investment, and so they are putting the maintenance burden on to their guests.

Expecting cleanup for a three month summer rental tenant is one thing.

Expecting that for a three day guest is another.

Also, I’d bet there were some very optimistic assumptions about overhead – retirees often make terrible landlords because they’re trying to hit targets for monthly profit and don’t have enough liquidity absorb cost increases. I suspect a lot of AirBnB hosts were in a similar boat where something like rates for cleaners going up really eats into the margin they are counting on.

The landlord who complains that rents aren't enough to make the mortgage, for example.

In an area like Silicon Valley, someone who buys a small property new and tries to rent it most definitely will not make the mortgage from rent, especially a single family house.